This document discusses enhanced exchange pinning fields observed in spin-valve structures with ultra-thin magnetic pinned layers and FeMn antiferromagnetic layers. Spin-valves using CoNiFe/Cu, NiFe/Cu, and CoFe/Cu multilayer systems were investigated. Those with ultra-thin pinned layers of approximately 0.5 nm exhibited high pinning fields of 800-900 Oe for CoNiFe/Cu and CoFe/Cu, and around 500 Oe for NiFe/Cu. Enhanced pinning fields were inversely related to pinned layer thickness. Giant magnetoresistance was also measured, decreasing from 3-4% to less than 2% for pinned layers below 0.8 nm
This document summarizes research on photovoltaic structures using thermally evaporated tin sulfide thin films. Key points:
- Tin sulfide films were deposited by thermal evaporation onto glass substrates in thicknesses ranging from 100-300nm.
- The films exhibited n-type conductivity at low thicknesses, transitioning to p-type at higher thicknesses. Bandgaps ranged from 2.1-1.7eV.
- CdS/SnS photovoltaic cells showed open circuit voltages up to 400mV, short circuit current densities up to 0.061mA/cm2, and conversion efficiencies up to 1.49% under 106mW/cm2 illumination.
Annealing Dependence of Exchange Bias in MnO/Ga1−xMnxAs HeterostructuresOleg Maksimov
The document discusses the annealing dependence of exchange bias in MnO/Ga1-xMnxAs heterostructures. It finds that as-grown Mn overlayers do not produce exchange coupling, and annealing is essential to create exchange bias signatures like loop shifting. X-ray photoelectron spectroscopy shows the cleanest exchange bias arises when the Mn overlayer is completely converted to MnO during annealing. Rapid thermal annealing of samples bonded with indium provides sufficient heating to oxidize the Mn layer to MnO and produce exchange bias, while unannealed samples do not exhibit this behavior.
The Indices of Refraction of Molecular-Beam Epitaxy–Grown BexZn1–xTe Ternary ...Oleg Maksimov
This document discusses a study that uses a combination of prism-coupling, reflectivity, and ellipsometric techniques to determine the indices of refraction (n) of molecular-beam epitaxy grown BexZn1-xTe thin films. Initially, prism-coupling measurements were used to obtain discrete n values and film thicknesses at specific wavelengths. Reflectivity data was then analyzed using the prism-coupling results to determine n dispersion below the bandgap. Ellipsometry was finally used to model n dispersion both below and above the bandgap, guided by the prior thickness and below-bandgap n data from the other techniques. The combination of these three methods allowed for accurate determination of n over a wide wavelength
Site-specific measurement of the giant magnetoresistance (GMR) of individual ...iosrjce
1. The document describes a new technique for measuring the giant magnetoresistance (GMR) of individual multilayer nanowires inside a scanning electron microscope (SEM).
2. Using nanomanipulators equipped with sharp tips, the resistance of NiFe/Pt multilayer nanowires can be measured at specific sites as an external magnetic field is varied.
3. Measurements of ~70nm diameter NiFe/Pt nanowires showed a GMR effect of up to 5.8% depending on layer thicknesses and field orientation. This new in-situ method allows precise characterization of nanowire magnetoresistance related to microstructure, geometry, and field orientation.
1994 atomic structure of longitudinal sections of a pitch based carbon fiber ...pmloscholte
1) STM images of longitudinal sections of pitch-based carbon fibers revealed a hexagonal superstructure with a periodicity of 14.9 A, indicating the top graphitic plane was rotated 9.5" from the underlying bulk.
2) Near defects, this superstructure was modulated with a (6 x fi)R30" pattern. The same modulation was found in images showing atomic resolution.
3) Power spectra of modulated regions contained extra peaks corresponding to the (6 x fi)R30" pattern, in addition to the six peaks from the hexagonal graphitic structure. This indicates the atomic structure is disturbed to a depth of at least two layers from the surface.
Exchange biasing of the ferromagnetic semiconductor Ga,Mn As by MnOOleg Maksimov
This document summarizes research on exchange biasing of the ferromagnetic semiconductor Ga1−xMnxAs with an antiferromagnetic MnO layer. Characterization using RBS, XPS, TEM, and XRR showed the formation of a MnO layer on Ga1−xMnxAs. SQUID magnetometry measurements exhibited an exchange field and enhanced coercivity, indicating exchange bias. The exchange and coercive fields varied with temperature and cooling field. Both cases where the Néel temperature of MnO was similar to or greater than the Curie temperature of Ga1−xMnxAs were investigated.
Nanoengineered Curie temperature in laterally patterned ferromagnetic semicon...Oleg Maksimov
This document summarizes research on manipulating the Curie temperature of ferromagnetic semiconductor heterostructures through nanolithography. The key findings are:
1) Patterning buried (Ga,Mn)As layers into nanowires exposes free surfaces along the sidewalls, allowing Mn interstitials to diffuse out during annealing.
2) Annealing nanowired samples leads to an enhanced Curie temperature and reduced resistivity compared to unpatterned samples, due to the removal of Mn interstitials.
3) The enhancement of Curie temperature is larger for narrower nanowires, as the smaller width facilitates the removal of Mn interstitials during annealing for a fixed time.
Self Organized Nanowires Evidence Of Dipolar Interactions From Fmr Measurementselpillo1003
1. The document presents ferromagnetic resonance (FMR) measurements on arrays of nickel nanowires that provide evidence of dipolar interactions between the nanowires.
2. The FMR measurements show that the angular variation of resonance field follows an uniaxial anisotropy pattern as expected from the shape of individual wires. However, the effective anisotropy is lower, indicating that dipolar interactions between wires decrease the single-wire anisotropy by around 20%.
3. Analysis of the dipolar fields produced by neighboring wires indicates this decrease in effective anisotropy is due to dipolar interactions opposing the shape anisotropy of individual wires. The FMR linewidth data also reflects the long-range order of the array.
This document summarizes research on photovoltaic structures using thermally evaporated tin sulfide thin films. Key points:
- Tin sulfide films were deposited by thermal evaporation onto glass substrates in thicknesses ranging from 100-300nm.
- The films exhibited n-type conductivity at low thicknesses, transitioning to p-type at higher thicknesses. Bandgaps ranged from 2.1-1.7eV.
- CdS/SnS photovoltaic cells showed open circuit voltages up to 400mV, short circuit current densities up to 0.061mA/cm2, and conversion efficiencies up to 1.49% under 106mW/cm2 illumination.
Annealing Dependence of Exchange Bias in MnO/Ga1−xMnxAs HeterostructuresOleg Maksimov
The document discusses the annealing dependence of exchange bias in MnO/Ga1-xMnxAs heterostructures. It finds that as-grown Mn overlayers do not produce exchange coupling, and annealing is essential to create exchange bias signatures like loop shifting. X-ray photoelectron spectroscopy shows the cleanest exchange bias arises when the Mn overlayer is completely converted to MnO during annealing. Rapid thermal annealing of samples bonded with indium provides sufficient heating to oxidize the Mn layer to MnO and produce exchange bias, while unannealed samples do not exhibit this behavior.
The Indices of Refraction of Molecular-Beam Epitaxy–Grown BexZn1–xTe Ternary ...Oleg Maksimov
This document discusses a study that uses a combination of prism-coupling, reflectivity, and ellipsometric techniques to determine the indices of refraction (n) of molecular-beam epitaxy grown BexZn1-xTe thin films. Initially, prism-coupling measurements were used to obtain discrete n values and film thicknesses at specific wavelengths. Reflectivity data was then analyzed using the prism-coupling results to determine n dispersion below the bandgap. Ellipsometry was finally used to model n dispersion both below and above the bandgap, guided by the prior thickness and below-bandgap n data from the other techniques. The combination of these three methods allowed for accurate determination of n over a wide wavelength
Site-specific measurement of the giant magnetoresistance (GMR) of individual ...iosrjce
1. The document describes a new technique for measuring the giant magnetoresistance (GMR) of individual multilayer nanowires inside a scanning electron microscope (SEM).
2. Using nanomanipulators equipped with sharp tips, the resistance of NiFe/Pt multilayer nanowires can be measured at specific sites as an external magnetic field is varied.
3. Measurements of ~70nm diameter NiFe/Pt nanowires showed a GMR effect of up to 5.8% depending on layer thicknesses and field orientation. This new in-situ method allows precise characterization of nanowire magnetoresistance related to microstructure, geometry, and field orientation.
1994 atomic structure of longitudinal sections of a pitch based carbon fiber ...pmloscholte
1) STM images of longitudinal sections of pitch-based carbon fibers revealed a hexagonal superstructure with a periodicity of 14.9 A, indicating the top graphitic plane was rotated 9.5" from the underlying bulk.
2) Near defects, this superstructure was modulated with a (6 x fi)R30" pattern. The same modulation was found in images showing atomic resolution.
3) Power spectra of modulated regions contained extra peaks corresponding to the (6 x fi)R30" pattern, in addition to the six peaks from the hexagonal graphitic structure. This indicates the atomic structure is disturbed to a depth of at least two layers from the surface.
Exchange biasing of the ferromagnetic semiconductor Ga,Mn As by MnOOleg Maksimov
This document summarizes research on exchange biasing of the ferromagnetic semiconductor Ga1−xMnxAs with an antiferromagnetic MnO layer. Characterization using RBS, XPS, TEM, and XRR showed the formation of a MnO layer on Ga1−xMnxAs. SQUID magnetometry measurements exhibited an exchange field and enhanced coercivity, indicating exchange bias. The exchange and coercive fields varied with temperature and cooling field. Both cases where the Néel temperature of MnO was similar to or greater than the Curie temperature of Ga1−xMnxAs were investigated.
Nanoengineered Curie temperature in laterally patterned ferromagnetic semicon...Oleg Maksimov
This document summarizes research on manipulating the Curie temperature of ferromagnetic semiconductor heterostructures through nanolithography. The key findings are:
1) Patterning buried (Ga,Mn)As layers into nanowires exposes free surfaces along the sidewalls, allowing Mn interstitials to diffuse out during annealing.
2) Annealing nanowired samples leads to an enhanced Curie temperature and reduced resistivity compared to unpatterned samples, due to the removal of Mn interstitials.
3) The enhancement of Curie temperature is larger for narrower nanowires, as the smaller width facilitates the removal of Mn interstitials during annealing for a fixed time.
Self Organized Nanowires Evidence Of Dipolar Interactions From Fmr Measurementselpillo1003
1. The document presents ferromagnetic resonance (FMR) measurements on arrays of nickel nanowires that provide evidence of dipolar interactions between the nanowires.
2. The FMR measurements show that the angular variation of resonance field follows an uniaxial anisotropy pattern as expected from the shape of individual wires. However, the effective anisotropy is lower, indicating that dipolar interactions between wires decrease the single-wire anisotropy by around 20%.
3. Analysis of the dipolar fields produced by neighboring wires indicates this decrease in effective anisotropy is due to dipolar interactions opposing the shape anisotropy of individual wires. The FMR linewidth data also reflects the long-range order of the array.
This document discusses the integration of a layered ferromagnetic composite material into a microwave propagation structure to enable tunable microwave device applications. The material combines the large saturation magnetization of ferromagnetic material with the low loss of dielectrics. Electromagnetic analysis was carried out to understand how the material properties are affected by the microwave field pattern and dc magnetic fields. Experimental results demonstrated tunable band stop filter and switch devices using the material, with over 50% tunability achieved in the filter using a 250 Oe dc field.
This document discusses the application of a ferromagnetic composite material in tunable microwave devices. Specifically:
- The composite material consists of ferromagnetic and insulating thin film layers that exhibit tunable intrinsic impedance when a DC magnetic field is applied.
- Several microwave devices were demonstrated using this composite material, including a tunable bandstop filter with 50% tunability, phase shifters with figures of merit of 35 deg/dB around 3 GHz and 7.8 deg/dB in the X band, and a magnetic switch with over 25 dB isolation and less than 1 dB insertion loss.
- The tunable behavior results from changes in the ferromagnetic resonance frequency of the composite material under an applied magnetic field, which
The document summarizes a study of the dielectric properties of nano-crystalline Mn-Zn ferrites. Samples of ZnxMn1-xFe2O4 where x ranges from 0.2 to 0.8 were synthesized using a solid-state route and characterized. The ac conductivity σ, dielectric constant ε', dielectric loss ε'', and loss tangent tan δ were measured from 100 Hz to 20 MHz. ε' and ε'' decreased with increasing frequency. σ was nearly frequency independent below 1 MHz and increased sharply above. The maximum dielectric constant and conductivity occurred for x=0.2, attributed to space charge polarization. The conduction mechanism was explained by electron hopping between Fe2+ and Fe
Gamry’s eQCM 10M™ is a rapid, impedance-scanning electrochemical quartz crystal microbalance (EQCM) that adds a valuable tool in the analytical toolbox of anyone investigating interfacial processes.
Growth and Magnetic properties of MnGeP2 thin filmsinventy
We have successfully grown MnGeP2 thin films on GaAs (100) substrate. A ferromagnetic transition near 320 K has been observed by temperature dependent magnetization and resistance measurements. Field dependent magnetization experiments have shown that the coercive fields at 5, 250, and 300 K are 3870, 1380 and 155 Oe, respectively. Magnetoresistance and Hall measurements have displayed that hole conduction is dominant in MnGeP2. PACS: 75.50.Pp, 75.70.-i, 85.70.-w, 73.50.-h
Negative resistance contribution of a domain-wall structure in a constricted ...Steven Theeuwen
This document discusses negative magnetoresistance contributions from domain walls in ferromagnetic point contacts. It finds that low resistance contacts show a magnetoresistance minimum around zero field of 0.4-1.3% between 1.5-293K, which is attributed to domain walls. High resistance contacts show behavior more consistent with anisotropic magnetoresistance of the uniformly magnetized channel material. Micromagnetic simulations predict a partially domain wall structure with domain walls at the edges of the constricted channel. For low resistance contacts, the domain walls are proposed to cause a resistance decrease through changes in boundary scattering, while for high resistance contacts the anisotropic magnetoresistance of the channel dominates.
This document summarizes research on the synthesis and characterization of superparamagnetic MgFe2O4 nanoparticles. Key points:
- MgFe2O4 nanoparticles were synthesized via a coprecipitation method and heat treatment.
- Magnetic measurements and neutron diffraction showed the nanoparticles exhibited superparamagnetic behavior, with ferrimagnetic ordering observed via neutron diffraction.
- Mössbauer spectroscopy studies correlated the superparamagnetic relaxation time of the nanoparticles with particle size and temperature, consistent with Neel theory.
This document discusses the optimization and simulation of Josephson junctions as switching elements. It begins with an introduction stating the need to optimize Josephson junction parameters and characteristics to increase switching speed. It then provides a brief review of the Josephson effect and properties of Josephson junctions. The rest of the document details a theoretical approach to estimating junction parameters, characteristics, and optimization methods, and using computer simulation to model the dynamic response of Josephson junctions to better understand their switching performance and speed.
This document presents experimental and theoretical studies on the elastic properties of molybdenum up to 12 GPa. Compressional and shear wave velocities were measured using ultrasonic interferometry combined with synchrotron x-ray diffraction. Both velocities increased linearly with pressure and agreed well with density functional theory calculations. Elastic moduli were derived from the velocity and density data using finite strain equations of state. The results were consistent with previous studies and provided elastic properties of molybdenum to higher pressures than previously reported.
1990 crystallization kinetics of thin amorphous in sb filmspmloscholte
1) Evaporated and sputtered InSb films have different crystallization properties. Evaporated films have a lower activation energy of 1.39 eV and crystallize by three-dimensional growth on existing nuclei.
2) Sputtered films have a higher activation energy of 2.7 eV and crystallize by nucleation and subsequent growth on the nuclei. The Avrami exponent indicates sputtered films require crystalline nuclei to form before crystallization can begin.
3) Transmission electron microscopy images show evaporated films have existing nuclei while sputtered films have no visible crystallites in the as-deposited state, requiring nucleation.
For two types of exchange-coupled composite perpendicular recording media (series A and series B), the switching mechanism was investigated using measurements of magnetic viscosity, hysteresis reptation, and reversibility. For series A, where the soft layer had much smaller anisotropy and stronger exchange than the hard layer, the measurements correlated with improved switchability, consistent with exchange-spring switching. For series B, where the soft layer had only slightly smaller anisotropy and stronger exchange, the media still showed improved switchability but no clear evidence of exchange-spring switching in the measurements. Thus the observations supported exchange-spring switching for series A but not for series B.
Magnetic and transport properties in thin film of fe2 cralDr. Vishal Jain
The document summarizes preliminary results on the magnetic and transport properties of a thin film of Fe2CrAl deposited on silicon substrate. While the bulk target used for deposition is purely ferromagnetic, the thin film shows coexistence of different magnetic phases due to its granular nature. This results in magnetic inhomogeneity and large negative temperature coefficient of resistance values of around 22%/K near 260 K. The film exhibits semiconducting behavior in resistivity and coupled electrical and magnetic properties near the ferromagnetic transition temperature of the ordered phase. The high and negative temperature coefficient of resistance values suggest potential for developing uncooled bolometric devices by manipulating the degree of disorder in such materials.
This document summarizes research on developing electrically tunable split-ring resonators (SRRs) using barium-strontium-titanate (BST) thick films. SRRs were fabricated on a multilayer substrate containing a BST layer to allow tuning of the resonance frequency with an applied voltage. Measurements found a tunability of around 12.5% when applying 140V. Simulations matched measurements well. This technology provides a low-cost way to fabricate tunable microwave devices with good reliability.
This document describes a new method for transferring aligned carbon nanotubes (ACNTs) onto substrates. The key steps are:
1) ACNTs are grown via chemical vapor deposition and functionalized in situ through bubbling hydrogen peroxide into the furnace during growth. This functionalizes the ACNT surface without damaging their structure.
2) A self-assembled monolayer of conjugated thiol molecules is formed on a gold substrate.
3) The functionalized ACNTs (f-ACNTs) are anchored to the gold substrate via covalent bonding between the f-ACNT surface groups and the thiol monolayer.
This "chemical transfer" method
The document summarizes research on developing a synthetic gecko tape adhesive by microfabricating arrays of flexible plastic pillars that mimic the structure of gecko foot hairs. Key findings include:
1) Initial attempts using rigid pillar arrays failed to achieve strong adhesion due to uneven surfaces preventing contact.
2) Flexible polyimide pillars were optimized through testing different diameters, heights, and densities.
3) Transferring the flexible pillar array to a soft backing dramatically improved adhesion by allowing more hairs to contact surfaces.
4) The synthetic gecko tape achieved adhesion forces comparable to geckos and could support weights, though durability requires further improvement.
Investigation of the Effects of Fullerene addition and Plasma Exposure on Opt...iosrjce
IOSR Journal of Applied Physics (IOSR-JAP) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Nanomechanical Characterization of CdSe QD-Polymer Nanocompositescurtistaylor80
Eddie McCumiskey's master's thesis presentation summarizes his research characterizing the mechanical properties of quantum dot (QD)-polymer nanocomposite films. His experiments showed that incorporating QDs into polymer films increased the films' elastic modulus and hardness in a linear fashion with respect to QD loading. The addition of QDs also reduced the films' viscoelasticity and creep. These findings have implications for improving the durability and reliability of QD-polymer hybrid devices.
Study of Structural and Dielectric properties of BaTiO3 Doped with Mg-Cu-Zn F...IJSRD
The magnetoelectric (ME) composites having the general formula, (x) Mg0.25Cu0.25Zn0.5Fe2O4 + (1-x) BaTiO3 (x=15%, 30%, 45%) were synthesized by sintering mixtures of highly ferroelectric BaTiO3 and highly magnetostrictive magnetic component Mg0.25Cu0.25Zn0.5Fe2O4. The presence of constituent phases of ferrite, ferroelectric and their composites were confirmed by X-ray diffraction (XRD) studies. Surface morphology of the samples has been investigated using Field Emission Scanning Electron Microscope (FESEM), which revealed uniform mixing of two phases. The variations in dielectric constant and dissipation factor as a function of frequency from 100 Hz to 1 MHz were measured in a Hioki LCR Hi-Tester. The dielectric constant and dielectric loss were found to decrease rapidly in the low frequency region and became almost constant in the high frequency region. The electrical conductivity deduced from the measured dielectric parameters has been analyzed and found that the conduction mechanism in these composites is in conformity with small polaron hopping model.
This document summarizes a model for thickness-mode oscillations in 1-3 composite piezoelectrics. The model treats the composite as an effective homogeneous medium when the lateral scale of the composite is sufficiently fine. Expressions are derived for the composite's material parameters in terms of the volume fraction and properties of the ceramic and polymer constituents. Examples show composites can have higher electromechanical coupling than ceramics alone due to partially freeing the ceramic's lateral clamping. However, properties cannot be optimized simultaneously and lower impedance comes at the cost of reduced coupling with lower ceramic volume fraction.
In-situ TEM studies of tribo-induced bonding modification in near-frictionles...Deepak Rajput
A presentation on "In-situ TEM studies of tribo-induced bonding modification in near-frictionless carbon films" made by Deepak Rajput. This presentation was based on "critical review of a paper," in All Things Carbon course offered at the University of Tennessee Space Insitute at Tullahoma in Fall 2009.
Al gan ultraviolet photodetectors grown by molecular beam epitaxy on si(111) ...Kal Tar
The performance of AlGaN metal-semiconductor-metal (MSM) photodetectors grown on Si(111) substrates is presented. Three key points:
1) An adequate AlN buffer layer is critical to achieve visible-blind photodetectors and electrically insulate the epitaxial film from the conductive substrate.
2) Increasing the Al content produced a transition from photoconductor to MSM photodiode behavior, as seen from responsivity, temporal response, and UV/visible contrast.
3) Contact metal affects photoconductive gain and UV/visible contrast. Pt/Ti/Au contacts showed higher contrast than Ti/Al contacts due to lower dark currents.
This document summarizes research on designing annular ring frequency selective surfaces (FSS) using different dielectric substrate materials. The research aims to achieve dual-band frequency response with controllable shift in resonance frequencies. FSS designs with annular ring elements are simulated using substrates like Teflon, Mica and FR4. Simulation results show dual transmission bands in C-band and X-band, with the frequencies shifting based on the dielectric constant of the material. Teflon provides the highest resonance frequencies while Mica and FR4 shift the frequencies down as their dielectric constants increase. The study demonstrates annular ring FSS can produce dual-band response with substrate material choice enabling predictable frequency shifts.
This document discusses the integration of a layered ferromagnetic composite material into a microwave propagation structure to enable tunable microwave device applications. The material combines the large saturation magnetization of ferromagnetic material with the low loss of dielectrics. Electromagnetic analysis was carried out to understand how the material properties are affected by the microwave field pattern and dc magnetic fields. Experimental results demonstrated tunable band stop filter and switch devices using the material, with over 50% tunability achieved in the filter using a 250 Oe dc field.
This document discusses the application of a ferromagnetic composite material in tunable microwave devices. Specifically:
- The composite material consists of ferromagnetic and insulating thin film layers that exhibit tunable intrinsic impedance when a DC magnetic field is applied.
- Several microwave devices were demonstrated using this composite material, including a tunable bandstop filter with 50% tunability, phase shifters with figures of merit of 35 deg/dB around 3 GHz and 7.8 deg/dB in the X band, and a magnetic switch with over 25 dB isolation and less than 1 dB insertion loss.
- The tunable behavior results from changes in the ferromagnetic resonance frequency of the composite material under an applied magnetic field, which
The document summarizes a study of the dielectric properties of nano-crystalline Mn-Zn ferrites. Samples of ZnxMn1-xFe2O4 where x ranges from 0.2 to 0.8 were synthesized using a solid-state route and characterized. The ac conductivity σ, dielectric constant ε', dielectric loss ε'', and loss tangent tan δ were measured from 100 Hz to 20 MHz. ε' and ε'' decreased with increasing frequency. σ was nearly frequency independent below 1 MHz and increased sharply above. The maximum dielectric constant and conductivity occurred for x=0.2, attributed to space charge polarization. The conduction mechanism was explained by electron hopping between Fe2+ and Fe
Gamry’s eQCM 10M™ is a rapid, impedance-scanning electrochemical quartz crystal microbalance (EQCM) that adds a valuable tool in the analytical toolbox of anyone investigating interfacial processes.
Growth and Magnetic properties of MnGeP2 thin filmsinventy
We have successfully grown MnGeP2 thin films on GaAs (100) substrate. A ferromagnetic transition near 320 K has been observed by temperature dependent magnetization and resistance measurements. Field dependent magnetization experiments have shown that the coercive fields at 5, 250, and 300 K are 3870, 1380 and 155 Oe, respectively. Magnetoresistance and Hall measurements have displayed that hole conduction is dominant in MnGeP2. PACS: 75.50.Pp, 75.70.-i, 85.70.-w, 73.50.-h
Negative resistance contribution of a domain-wall structure in a constricted ...Steven Theeuwen
This document discusses negative magnetoresistance contributions from domain walls in ferromagnetic point contacts. It finds that low resistance contacts show a magnetoresistance minimum around zero field of 0.4-1.3% between 1.5-293K, which is attributed to domain walls. High resistance contacts show behavior more consistent with anisotropic magnetoresistance of the uniformly magnetized channel material. Micromagnetic simulations predict a partially domain wall structure with domain walls at the edges of the constricted channel. For low resistance contacts, the domain walls are proposed to cause a resistance decrease through changes in boundary scattering, while for high resistance contacts the anisotropic magnetoresistance of the channel dominates.
This document summarizes research on the synthesis and characterization of superparamagnetic MgFe2O4 nanoparticles. Key points:
- MgFe2O4 nanoparticles were synthesized via a coprecipitation method and heat treatment.
- Magnetic measurements and neutron diffraction showed the nanoparticles exhibited superparamagnetic behavior, with ferrimagnetic ordering observed via neutron diffraction.
- Mössbauer spectroscopy studies correlated the superparamagnetic relaxation time of the nanoparticles with particle size and temperature, consistent with Neel theory.
This document discusses the optimization and simulation of Josephson junctions as switching elements. It begins with an introduction stating the need to optimize Josephson junction parameters and characteristics to increase switching speed. It then provides a brief review of the Josephson effect and properties of Josephson junctions. The rest of the document details a theoretical approach to estimating junction parameters, characteristics, and optimization methods, and using computer simulation to model the dynamic response of Josephson junctions to better understand their switching performance and speed.
This document presents experimental and theoretical studies on the elastic properties of molybdenum up to 12 GPa. Compressional and shear wave velocities were measured using ultrasonic interferometry combined with synchrotron x-ray diffraction. Both velocities increased linearly with pressure and agreed well with density functional theory calculations. Elastic moduli were derived from the velocity and density data using finite strain equations of state. The results were consistent with previous studies and provided elastic properties of molybdenum to higher pressures than previously reported.
1990 crystallization kinetics of thin amorphous in sb filmspmloscholte
1) Evaporated and sputtered InSb films have different crystallization properties. Evaporated films have a lower activation energy of 1.39 eV and crystallize by three-dimensional growth on existing nuclei.
2) Sputtered films have a higher activation energy of 2.7 eV and crystallize by nucleation and subsequent growth on the nuclei. The Avrami exponent indicates sputtered films require crystalline nuclei to form before crystallization can begin.
3) Transmission electron microscopy images show evaporated films have existing nuclei while sputtered films have no visible crystallites in the as-deposited state, requiring nucleation.
For two types of exchange-coupled composite perpendicular recording media (series A and series B), the switching mechanism was investigated using measurements of magnetic viscosity, hysteresis reptation, and reversibility. For series A, where the soft layer had much smaller anisotropy and stronger exchange than the hard layer, the measurements correlated with improved switchability, consistent with exchange-spring switching. For series B, where the soft layer had only slightly smaller anisotropy and stronger exchange, the media still showed improved switchability but no clear evidence of exchange-spring switching in the measurements. Thus the observations supported exchange-spring switching for series A but not for series B.
Magnetic and transport properties in thin film of fe2 cralDr. Vishal Jain
The document summarizes preliminary results on the magnetic and transport properties of a thin film of Fe2CrAl deposited on silicon substrate. While the bulk target used for deposition is purely ferromagnetic, the thin film shows coexistence of different magnetic phases due to its granular nature. This results in magnetic inhomogeneity and large negative temperature coefficient of resistance values of around 22%/K near 260 K. The film exhibits semiconducting behavior in resistivity and coupled electrical and magnetic properties near the ferromagnetic transition temperature of the ordered phase. The high and negative temperature coefficient of resistance values suggest potential for developing uncooled bolometric devices by manipulating the degree of disorder in such materials.
This document summarizes research on developing electrically tunable split-ring resonators (SRRs) using barium-strontium-titanate (BST) thick films. SRRs were fabricated on a multilayer substrate containing a BST layer to allow tuning of the resonance frequency with an applied voltage. Measurements found a tunability of around 12.5% when applying 140V. Simulations matched measurements well. This technology provides a low-cost way to fabricate tunable microwave devices with good reliability.
This document describes a new method for transferring aligned carbon nanotubes (ACNTs) onto substrates. The key steps are:
1) ACNTs are grown via chemical vapor deposition and functionalized in situ through bubbling hydrogen peroxide into the furnace during growth. This functionalizes the ACNT surface without damaging their structure.
2) A self-assembled monolayer of conjugated thiol molecules is formed on a gold substrate.
3) The functionalized ACNTs (f-ACNTs) are anchored to the gold substrate via covalent bonding between the f-ACNT surface groups and the thiol monolayer.
This "chemical transfer" method
The document summarizes research on developing a synthetic gecko tape adhesive by microfabricating arrays of flexible plastic pillars that mimic the structure of gecko foot hairs. Key findings include:
1) Initial attempts using rigid pillar arrays failed to achieve strong adhesion due to uneven surfaces preventing contact.
2) Flexible polyimide pillars were optimized through testing different diameters, heights, and densities.
3) Transferring the flexible pillar array to a soft backing dramatically improved adhesion by allowing more hairs to contact surfaces.
4) The synthetic gecko tape achieved adhesion forces comparable to geckos and could support weights, though durability requires further improvement.
Investigation of the Effects of Fullerene addition and Plasma Exposure on Opt...iosrjce
IOSR Journal of Applied Physics (IOSR-JAP) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Nanomechanical Characterization of CdSe QD-Polymer Nanocompositescurtistaylor80
Eddie McCumiskey's master's thesis presentation summarizes his research characterizing the mechanical properties of quantum dot (QD)-polymer nanocomposite films. His experiments showed that incorporating QDs into polymer films increased the films' elastic modulus and hardness in a linear fashion with respect to QD loading. The addition of QDs also reduced the films' viscoelasticity and creep. These findings have implications for improving the durability and reliability of QD-polymer hybrid devices.
Study of Structural and Dielectric properties of BaTiO3 Doped with Mg-Cu-Zn F...IJSRD
The magnetoelectric (ME) composites having the general formula, (x) Mg0.25Cu0.25Zn0.5Fe2O4 + (1-x) BaTiO3 (x=15%, 30%, 45%) were synthesized by sintering mixtures of highly ferroelectric BaTiO3 and highly magnetostrictive magnetic component Mg0.25Cu0.25Zn0.5Fe2O4. The presence of constituent phases of ferrite, ferroelectric and their composites were confirmed by X-ray diffraction (XRD) studies. Surface morphology of the samples has been investigated using Field Emission Scanning Electron Microscope (FESEM), which revealed uniform mixing of two phases. The variations in dielectric constant and dissipation factor as a function of frequency from 100 Hz to 1 MHz were measured in a Hioki LCR Hi-Tester. The dielectric constant and dielectric loss were found to decrease rapidly in the low frequency region and became almost constant in the high frequency region. The electrical conductivity deduced from the measured dielectric parameters has been analyzed and found that the conduction mechanism in these composites is in conformity with small polaron hopping model.
This document summarizes a model for thickness-mode oscillations in 1-3 composite piezoelectrics. The model treats the composite as an effective homogeneous medium when the lateral scale of the composite is sufficiently fine. Expressions are derived for the composite's material parameters in terms of the volume fraction and properties of the ceramic and polymer constituents. Examples show composites can have higher electromechanical coupling than ceramics alone due to partially freeing the ceramic's lateral clamping. However, properties cannot be optimized simultaneously and lower impedance comes at the cost of reduced coupling with lower ceramic volume fraction.
In-situ TEM studies of tribo-induced bonding modification in near-frictionles...Deepak Rajput
A presentation on "In-situ TEM studies of tribo-induced bonding modification in near-frictionless carbon films" made by Deepak Rajput. This presentation was based on "critical review of a paper," in All Things Carbon course offered at the University of Tennessee Space Insitute at Tullahoma in Fall 2009.
Al gan ultraviolet photodetectors grown by molecular beam epitaxy on si(111) ...Kal Tar
The performance of AlGaN metal-semiconductor-metal (MSM) photodetectors grown on Si(111) substrates is presented. Three key points:
1) An adequate AlN buffer layer is critical to achieve visible-blind photodetectors and electrically insulate the epitaxial film from the conductive substrate.
2) Increasing the Al content produced a transition from photoconductor to MSM photodiode behavior, as seen from responsivity, temporal response, and UV/visible contrast.
3) Contact metal affects photoconductive gain and UV/visible contrast. Pt/Ti/Au contacts showed higher contrast than Ti/Al contacts due to lower dark currents.
This document summarizes research on designing annular ring frequency selective surfaces (FSS) using different dielectric substrate materials. The research aims to achieve dual-band frequency response with controllable shift in resonance frequencies. FSS designs with annular ring elements are simulated using substrates like Teflon, Mica and FR4. Simulation results show dual transmission bands in C-band and X-band, with the frequencies shifting based on the dielectric constant of the material. Teflon provides the highest resonance frequencies while Mica and FR4 shift the frequencies down as their dielectric constants increase. The study demonstrates annular ring FSS can produce dual-band response with substrate material choice enabling predictable frequency shifts.
Study of Microstructural, Electrical and Dielectric Properties of La0.9Pb0.1M...Scientific Review SR
The present work studies the microstructural and electrical properties of La0.9Pb0.1MnO3 and La0.8Y0.1Pb0.1MnO3 ceramics synthesized by solid-state route method. Microstructure and elemental analysis of both samples were carried out by field emission scanning electron microscope (FESEM) and energy dispersive spectroscopy (EDS) method, respectively. Phase analysis by X-ray diffraction (XRD) indicated formation of single phase distorted structure. The XRD data were further analyzed by Rietveld refinement technique. Raman analysis reveals that Y atom substitutes La site into the LPMO with shifting of phonon modes. The temperature variation of resistivity of undoped and Y-doped La0.9Pb0.1MnO3 samples have been investigated. The electrical resistivity as a function of temperature showed that all samples undergo an metal-insulator (M-I) transition having a peak at transition temperature TMI. Y-doping increases the resistivity and the metal-insulator transition temperature (TMI) shifts to lower temperature. The temperature-dependent resistivity for temperatures less than metal-insulator transition is explained in terms the quadratic temperature dependence and for T > TMI, thermally activated conduction (TAC) is appropriate. Variation of frequency dispersion in permittivity and loss pattern due to La-site substitution in LPMO was observed in the dielectric response curve.
The effect of magnetic field direction on thermoelectric and thermomagnetic c...Muhammid Al-Baghdadi
This document investigates the effect of magnetic field direction on thermoelectric and thermomagnetic coefficients of undoped single crystalline InSb at room temperature. It describes how samples of InSb were tested under varying magnetic fields and temperature gradients to measure the Seebeck and Nernst coefficients. The results showed that the Seebeck coefficient depended only on the temperature gradient, while the Nernst coefficient depended on both the temperature gradient and magnetic field. However, the values of the thermoelectric and thermomagnetic coefficients were found to be independent of the direction of the applied magnetic field with respect to the InSb sample surface.
This document discusses magnetic viscosity, hysteresis reptation, and their relationship to adjacent track interference (ATI) in perpendicular magnetic recording media. It presents results from studies of these phenomena on a three-layer exchange-coupled composite perpendicular recording media with graded anisotropy. Magnetic viscosity and reptation both showed a second-order logarithmic time dependence. Viscosity correlated with field reptation but not remanence reptation. Remarkably, ATI correlated strongly with remanence reptation across all media samples, suggesting remanence reptation is a useful technique for studying how exchange and thermal effects influence switchability and ATI in magnetic media.
The Muon g-2 experiment at Fermilab aims to precisely measure the anomalous magnetic moment of the muon to test predictions of the Standard Model. Current efforts involve shaping the magnetic field in the storage ring to reduce uncertainties. Laminating over 9,000 small iron foils around the ring poles has improved field consistency from 200 ppm to under 25 ppm azimuthally. Further reductions to below 0.5 ppm are expected to achieve the experiment's goal of limiting systematic uncertainties to 140 ppb.
The International Journal of Engineering and Sciencetheijes
This document summarizes a study on enhancing the properties of porous gallium nitride (GaN) using different intensities of ultraviolet (UV) electrochemical etching. GaN samples were etched at various current densities of UV illumination and characterized using scanning electron microscopy, photoluminescence spectroscopy, and Raman spectroscopy. The results showed that increasing the current density led to larger pore sizes, higher photoluminescence intensity, and small blue shifts and peak broadening in the Raman spectra, indicating relaxation of stress in the porous GaN layers.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Sputtering of Ga-doped ZnO nanocoatings on silicon for piezoelectric transducersMariya Aleksandrova
This talk was delivered on the 8TH INTERNATIONAL SCIENTIFIC CONFERENCE “TechSys 2019” – ENGINEERING, TECHNOLOGIES AND SYSTEMS, Technical University of Sofia, Plovdiv Branch, 16-18 May 2019. The research is funded by BNSF’s grant KП06-Н27/1.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Amorphous-nano-crystalline silicon composite thin films (a-nc-Si:H) samples were synthesized by
Plasma Enhanced Chemical Vapor Deposition technique. The measurement of DC conductivities was
accomplished using Dielectric spectroscopy (Impedance Spectroscopy) in wide frequency and temperature range.
In analysis of impedance data, two approaches were tested: the Debye type equivalent circuit with two parallel R
and CPEs (constant phase elements) and modified one, with tree parallel R and CPEs including crystal grain
boundary effects. It was found that the later better fits to experimental results properly describes crystal grains
dielectric effect and hydrogen concentration indicating presence of strain. The amorphous matrix showed larger
resistance and lower capacity than nano-crystal phase. Also it was found that composite silicon thin film cannot
be properly described by equivalent circuit only with resistors and constant phase elements in serial relation
The document discusses computational screening of 2D materials for different applications. It describes research being conducted at Allama Iqbal Open University on using computational methods to predict properties of 2D materials and study their potential applications in areas like photocatalysis, gas sensing, and thermoelectric devices. The research group is computationally investigating various 2D materials like MoSi2N4, WGe2N4, and WSi2N4 to understand their structural stability, electronic properties, and suitability for applications. The introduction provides background on 2D materials and their unique properties compared to bulk materials.
This document summarizes research on measuring the giant magnetoresistance (GMR) in cobalt/copper spin valves using nanometer-sized point contacts. Key findings include:
1) Measurements show strong differences between devices and GMR ratios decrease with increasing bias current, attributed to probing only a few magnetic domains rather than averaging over many.
2) For one device, two distinct GMR plateaus develop with increasing bias, with plateau levels depending on bias polarity and field sweep direction.
3) Effects are attributed to current-induced changes in magnetization from spin transfer of incoherent magnons and self-field effects rather than Joule heating or coherent magnon rotation.
10.1016-j.mssp.2015.01.037-Electrochemical investigation of graphene_nanoporo...Mahdi Robat Sarpoushi
This study investigated the effect of mixing graphene nanosheets and nanoporous carbon black on the surface morphology and electrochemical performance of electrodes prepared for supercapacitors. Electrodes containing 80% nanoporous carbon black, 10% graphene nanosheets, and 10% PTFE binder showed the highest specific capacitance of 10.22 F/g. The addition of nanoporous carbon black increased the proportion of outer charge stored on the electrode relative to the total charge stored, indicating higher current response and voltage reversal at the end potentials. Scanning electron microscopy images showed that adding nanoporous carbon black particles arranged the graphene nanosheets in different directions, increasing the specific surface area and changing diffusion characteristics to improve capacitance and reversibility
Magnetic materials form magnetic domains to minimize their magnetostatic energy. Domain walls separate domains with different magnetization orientations. Bloch walls have spins rotating continuously across the wall, while Neel walls have spins rotating in the plane of the wall. The equilibrium domain size and wall thickness are determined by a balance of exchange, anisotropy, magnetostatic, and wall energies. Various techniques like SEMPA, MFM, and magneto-optical imaging are used to observe domain structures with high resolution.
Investigation of heat transfer through cnt composites focusing on conduction ...iaemedu
This document summarizes a study that investigated the heat transfer properties of carbon nanotube (CNT) composites, with a focus on conduction mode heat transfer. Multi-wall carbon nanotubes were synthesized using chemical vapor deposition inside anodic aluminum oxide templates to create aligned CNT composites. Randomly oriented CNT and graphite films were also prepared. Specific heat capacity and thermal conductivity measurements from 300-400K revealed that aligned CNT composites had higher thermal conductivity than randomly oriented films, demonstrating the anisotropic heat transfer properties of aligned CNT structures. Randomly oriented CNT and graphite films showed similar thermal properties.
Investigation of heat transfer through cnt composites focusing on conduction ...IAEME Publication
1. The document investigates heat transfer through carbon nanotube composites, focusing on the conduction mode.
2. It summarizes the synthesis and preparation of aligned multi-walled carbon nanotube samples embedded in anodic aluminum oxide templates, as well as randomly oriented films of multi-walled carbon nanotubes, single-walled carbon nanotubes, and graphite powder.
3. The specific heat and thermal conductivity of the samples are measured from 300 to 400K. The specific heat of the aligned nanotube sample has weaker temperature dependence than the random films and bulk graphite. The thermal conductivity of the aligned sample increases with temperature, while the random films and graphite show a
Investigation of heat transfer through cnt composites focusing on conduction ...IAEME Publication
This document summarizes a study that investigated the heat transfer properties of carbon nanotube (CNT) composites, with a focus on conduction mode heat transfer. Multi-wall carbon nanotubes were synthesized using chemical vapor deposition inside anodic aluminum oxide templates to create aligned CNT composites. Randomly oriented CNT and graphite films were also prepared. Specific heat capacity and thermal conductivity were measured for the different materials from 300-400K using an AC calorimetric technique. Results showed the aligned CNT composite had higher thermal conductivity than the random films, demonstrating the anisotropic heat transfer along the CNT axes.
Investigation of heat transfer through cnt composites focusing on conduction ...iaemedu
1. The document investigates the heat transfer properties of carbon nanotube composites, focusing on the conduction mode of heat transfer.
2. It analyzes the specific heat and thermal conductivity of aligned multi-walled carbon nanotubes embedded in anodic aluminum oxide templates, as well as randomly oriented films of multi-walled carbon nanotubes, single-walled carbon nanotubes, and graphite powder.
3. The results show that the specific heat of the randomly oriented films is similar to bulk graphite powder, while the aligned nanotubes have a weaker temperature dependence. The thermal conductivity of the randomly oriented films behaves similarly to graphite and is dominated by phonon boundary scattering, while
Similar to Enhanced Exchange Pinning Field For Fe Mn Spin Valves (20)
Observability Concepts EVERY Developer Should Know -- DeveloperWeek Europe.pdfPaige Cruz
Monitoring and observability aren’t traditionally found in software curriculums and many of us cobble this knowledge together from whatever vendor or ecosystem we were first introduced to and whatever is a part of your current company’s observability stack.
While the dev and ops silo continues to crumble….many organizations still relegate monitoring & observability as the purview of ops, infra and SRE teams. This is a mistake - achieving a highly observable system requires collaboration up and down the stack.
I, a former op, would like to extend an invitation to all application developers to join the observability party will share these foundational concepts to build on:
TrustArc Webinar - 2024 Global Privacy SurveyTrustArc
How does your privacy program stack up against your peers? What challenges are privacy teams tackling and prioritizing in 2024?
In the fifth annual Global Privacy Benchmarks Survey, we asked over 1,800 global privacy professionals and business executives to share their perspectives on the current state of privacy inside and outside of their organizations. This year’s report focused on emerging areas of importance for privacy and compliance professionals, including considerations and implications of Artificial Intelligence (AI) technologies, building brand trust, and different approaches for achieving higher privacy competence scores.
See how organizational priorities and strategic approaches to data security and privacy are evolving around the globe.
This webinar will review:
- The top 10 privacy insights from the fifth annual Global Privacy Benchmarks Survey
- The top challenges for privacy leaders, practitioners, and organizations in 2024
- Key themes to consider in developing and maintaining your privacy program
In the rapidly evolving landscape of technologies, XML continues to play a vital role in structuring, storing, and transporting data across diverse systems. The recent advancements in artificial intelligence (AI) present new methodologies for enhancing XML development workflows, introducing efficiency, automation, and intelligent capabilities. This presentation will outline the scope and perspective of utilizing AI in XML development. The potential benefits and the possible pitfalls will be highlighted, providing a balanced view of the subject.
We will explore the capabilities of AI in understanding XML markup languages and autonomously creating structured XML content. Additionally, we will examine the capacity of AI to enrich plain text with appropriate XML markup. Practical examples and methodological guidelines will be provided to elucidate how AI can be effectively prompted to interpret and generate accurate XML markup.
Further emphasis will be placed on the role of AI in developing XSLT, or schemas such as XSD and Schematron. We will address the techniques and strategies adopted to create prompts for generating code, explaining code, or refactoring the code, and the results achieved.
The discussion will extend to how AI can be used to transform XML content. In particular, the focus will be on the use of AI XPath extension functions in XSLT, Schematron, Schematron Quick Fixes, or for XML content refactoring.
The presentation aims to deliver a comprehensive overview of AI usage in XML development, providing attendees with the necessary knowledge to make informed decisions. Whether you’re at the early stages of adopting AI or considering integrating it in advanced XML development, this presentation will cover all levels of expertise.
By highlighting the potential advantages and challenges of integrating AI with XML development tools and languages, the presentation seeks to inspire thoughtful conversation around the future of XML development. We’ll not only delve into the technical aspects of AI-powered XML development but also discuss practical implications and possible future directions.
Climate Impact of Software Testing at Nordic Testing DaysKari Kakkonen
My slides at Nordic Testing Days 6.6.2024
Climate impact / sustainability of software testing discussed on the talk. ICT and testing must carry their part of global responsibility to help with the climat warming. We can minimize the carbon footprint but we can also have a carbon handprint, a positive impact on the climate. Quality characteristics can be added with sustainability, and then measured continuously. Test environments can be used less, and in smaller scale and on demand. Test techniques can be used in optimizing or minimizing number of tests. Test automation can be used to speed up testing.
Removing Uninteresting Bytes in Software FuzzingAftab Hussain
Imagine a world where software fuzzing, the process of mutating bytes in test seeds to uncover hidden and erroneous program behaviors, becomes faster and more effective. A lot depends on the initial seeds, which can significantly dictate the trajectory of a fuzzing campaign, particularly in terms of how long it takes to uncover interesting behaviour in your code. We introduce DIAR, a technique designed to speedup fuzzing campaigns by pinpointing and eliminating those uninteresting bytes in the seeds. Picture this: instead of wasting valuable resources on meaningless mutations in large, bloated seeds, DIAR removes the unnecessary bytes, streamlining the entire process.
In this work, we equipped AFL, a popular fuzzer, with DIAR and examined two critical Linux libraries -- Libxml's xmllint, a tool for parsing xml documents, and Binutil's readelf, an essential debugging and security analysis command-line tool used to display detailed information about ELF (Executable and Linkable Format). Our preliminary results show that AFL+DIAR does not only discover new paths more quickly but also achieves higher coverage overall. This work thus showcases how starting with lean and optimized seeds can lead to faster, more comprehensive fuzzing campaigns -- and DIAR helps you find such seeds.
- These are slides of the talk given at IEEE International Conference on Software Testing Verification and Validation Workshop, ICSTW 2022.
Why You Should Replace Windows 11 with Nitrux Linux 3.5.0 for enhanced perfor...SOFTTECHHUB
The choice of an operating system plays a pivotal role in shaping our computing experience. For decades, Microsoft's Windows has dominated the market, offering a familiar and widely adopted platform for personal and professional use. However, as technological advancements continue to push the boundaries of innovation, alternative operating systems have emerged, challenging the status quo and offering users a fresh perspective on computing.
One such alternative that has garnered significant attention and acclaim is Nitrux Linux 3.5.0, a sleek, powerful, and user-friendly Linux distribution that promises to redefine the way we interact with our devices. With its focus on performance, security, and customization, Nitrux Linux presents a compelling case for those seeking to break free from the constraints of proprietary software and embrace the freedom and flexibility of open-source computing.
GraphSummit Singapore | The Future of Agility: Supercharging Digital Transfor...Neo4j
Leonard Jayamohan, Partner & Generative AI Lead, Deloitte
This keynote will reveal how Deloitte leverages Neo4j’s graph power for groundbreaking digital twin solutions, achieving a staggering 100x performance boost. Discover the essential role knowledge graphs play in successful generative AI implementations. Plus, get an exclusive look at an innovative Neo4j + Generative AI solution Deloitte is developing in-house.
Cosa hanno in comune un mattoncino Lego e la backdoor XZ?Speck&Tech
ABSTRACT: A prima vista, un mattoncino Lego e la backdoor XZ potrebbero avere in comune il fatto di essere entrambi blocchi di costruzione, o dipendenze di progetti creativi e software. La realtà è che un mattoncino Lego e il caso della backdoor XZ hanno molto di più di tutto ciò in comune.
Partecipate alla presentazione per immergervi in una storia di interoperabilità, standard e formati aperti, per poi discutere del ruolo importante che i contributori hanno in una comunità open source sostenibile.
BIO: Sostenitrice del software libero e dei formati standard e aperti. È stata un membro attivo dei progetti Fedora e openSUSE e ha co-fondato l'Associazione LibreItalia dove è stata coinvolta in diversi eventi, migrazioni e formazione relativi a LibreOffice. In precedenza ha lavorato a migrazioni e corsi di formazione su LibreOffice per diverse amministrazioni pubbliche e privati. Da gennaio 2020 lavora in SUSE come Software Release Engineer per Uyuni e SUSE Manager e quando non segue la sua passione per i computer e per Geeko coltiva la sua curiosità per l'astronomia (da cui deriva il suo nickname deneb_alpha).
Infrastructure Challenges in Scaling RAG with Custom AI modelsZilliz
Building Retrieval-Augmented Generation (RAG) systems with open-source and custom AI models is a complex task. This talk explores the challenges in productionizing RAG systems, including retrieval performance, response synthesis, and evaluation. We’ll discuss how to leverage open-source models like text embeddings, language models, and custom fine-tuned models to enhance RAG performance. Additionally, we’ll cover how BentoML can help orchestrate and scale these AI components efficiently, ensuring seamless deployment and management of RAG systems in the cloud.
Programming Foundation Models with DSPy - Meetup SlidesZilliz
Prompting language models is hard, while programming language models is easy. In this talk, I will discuss the state-of-the-art framework DSPy for programming foundation models with its powerful optimizers and runtime constraint system.
Essentials of Automations: The Art of Triggers and Actions in FMESafe Software
In this second installment of our Essentials of Automations webinar series, we’ll explore the landscape of triggers and actions, guiding you through the nuances of authoring and adapting workspaces for seamless automations. Gain an understanding of the full spectrum of triggers and actions available in FME, empowering you to enhance your workspaces for efficient automation.
We’ll kick things off by showcasing the most commonly used event-based triggers, introducing you to various automation workflows like manual triggers, schedules, directory watchers, and more. Plus, see how these elements play out in real scenarios.
Whether you’re tweaking your current setup or building from the ground up, this session will arm you with the tools and insights needed to transform your FME usage into a powerhouse of productivity. Join us to discover effective strategies that simplify complex processes, enhancing your productivity and transforming your data management practices with FME. Let’s turn complexity into clarity and make your workspaces work wonders!
Communications Mining Series - Zero to Hero - Session 1DianaGray10
This session provides introduction to UiPath Communication Mining, importance and platform overview. You will acquire a good understand of the phases in Communication Mining as we go over the platform with you. Topics covered:
• Communication Mining Overview
• Why is it important?
• How can it help today’s business and the benefits
• Phases in Communication Mining
• Demo on Platform overview
• Q/A
Best 20 SEO Techniques To Improve Website Visibility In SERPPixlogix Infotech
Boost your website's visibility with proven SEO techniques! Our latest blog dives into essential strategies to enhance your online presence, increase traffic, and rank higher on search engines. From keyword optimization to quality content creation, learn how to make your site stand out in the crowded digital landscape. Discover actionable tips and expert insights to elevate your SEO game.
How to Get CNIC Information System with Paksim Ga.pptxdanishmna97
Pakdata Cf is a groundbreaking system designed to streamline and facilitate access to CNIC information. This innovative platform leverages advanced technology to provide users with efficient and secure access to their CNIC details.
How to Get CNIC Information System with Paksim Ga.pptx
Enhanced Exchange Pinning Field For Fe Mn Spin Valves
1. ~ H Journalof
magnetism
N
ELSEVIER Journal of Magnetism and Magnetic Materials 168 (1997) L233 L236
and
magnetic
materials
L e t t e r to t h e E d i t o r
Enhanced exchange pinning field for FeMn spin-valves
S.L. B u r k e t t * , J.C. L u s t h , J.L. B r e s o w a r 1, M . R . P a r k e r z
The Center for Materials for Information Technology, The University of Alabama, Tuscaloosa, ilL 35487-0209, USA
Received 2 December 1996
Abstract
Enhanced exchangepinning is observed in spin-valves with ultra-thin magnetic pinned layers and FeMn antiferromag-
netic layers. In this study, three magnetic material multilayer systems, CoNiFe/Cu, NiFe/Cu, and CoFe/Cu, are
investigated. Spin-valves with ultra-thin pinned layers (~0.5 nm) exhibit exchange pinning fields as high as 800-900 Oe
in CoNiFe/Cu and CoFe/Cu multilayers while a pinning field of approximately 500 Oe is obtained for NiFe/Cu
multilayers.
PACS: 75.30; 75.50; 75.70
Keywords: Spin-valve; Multilayer systems; Giant magnetoresistance;FeMn; Antiferromagneticlayers
1. I n t r o d u c t i o n sponse to small magnetic fields. They are also
becoming potentially important media candidates
Spin-valve thin-film multilayer structures are for magnetic solid state memory (MRAM) [1].
promising candidates for next generation read In these material structures, the magnetic orienta-
heads in high-density magnetic recording applica- tion of one layer is controlled by the presence of
tions due to their high sensitivity and linear re- an antiferromagnetic material, while another layer
is essentially free to rotate when exposed to
an applied magnetic field. The change in relative
orientation of the two layers will produce a
* Correspondence address: Department of Electrical Engin- magnetoresistive (MR) effect [1]. This effect is
eering, University of Alabama, Tuscaloosa, AL 35487-0286, achieved in a spin-valve with the 'free' and 'pinned'
USA. Fax: (205) 348-6959; e-mail: sburkett@coe.eng.ua.edu.
magnetic layers separated by a nonmagnetic
Current address: School of Physics, Georgia Institute of
Technology, Atlanta, GA 30332-0430, USA. metallic spacer, such as Cu. Spin-valves exhibit
2 Current address: The Department of Electrical Engineering, a magnetoresistance substantially larger than
The University of South Alabama, Mobile, AL 36688, USA. the current-generation read heads that employ
0304-8853/97/$17.00 O 1997 Elsevier Science B.V. All rights reserved
PII S 0 3 0 4 - 8 8 5 3 ( 9 6 ) 0 0 7 3 0 - 5
2. LETTER TO THE EDITOR
L234 S.L. Burkett et al. / Journal of Magnetism and Magnetic Materials 168 (1997) L233-L236
anisotropic magnetoresistance (AMR) [2]. This with a Dektak IIa profilometer. The spin-valves are
parameter is highly dependent upon the selection of composed of a 10 nm Ta seed layer followed by
materials and the thickness of the thin films making a 10 nm magnetic free layer, a 2.4 nm Cu spacer,
up the multilayer stack. An excellent overview ex- a variable (~0.5-4.0 rim) magnetic pinned layer,
plaining the advantages and disadvantages for ma- 15 nm F%0Mnso pinning layer, and a 5.0 nm Ta
terials choice and various multilayer layouts in capping layer. Three magnetic multilayer systems
a spin-valve structure is given by Kools [1]. are used: Co45Ni30Fezs/Cu, NisoFe20/Cu, and
Practical spin-valve devices for ultra-high den- Co90Fel0/Cu. It has been shown by other re-
sity record heads can involve patterned rectangular searchers that the Co-rich ternary alloy gives en-
mesoscopic elements with 'heights' (i.e. lateral di- hanced MR ratios and low coercivity at this
mensions) as small as 0.5 gm. Given that Hp is composition [6]. In the case of CoFe/Cu spin-
required to be directed orthogonal to the long axis valves, a single layer of CoFe makes up the mag-
of the element, it follows that Hp values must be of netic pinned layer as in the other material systems,
sufficient magnitude (>>250 Oe) [3] to resist de- however, a multilayer of CoFe 1.7 nm/(Cu 0.8 nm/
magnetizing effects. The latter are approximately CoFe 1.7 nm)s is used as the free layer. This multi-
proportional to film thickness while Hp values fol- layered free magnetic layer has been effective in
low a 1/thickness dependence rather closely. producing spin-valves with higher G M R ratios and
Hamakawa et al., for example, have illustrated this lower coercivities compared to spin-valves fab-
thickness dependence for spin-valves utilizing anti- ricated with a single layer of CoFe as the free
ferromagnetic NiO layers [4]. Kim et al. have demon- layer [7].
strated high-exchange anisotropy fields for bilayers For evaluation of spin-valve performance, mag-
of NiFe/FeMn deposited on silicon substrates netic properties are measured using a four-point
when the thickness of the NiFe film is 3.0 nm [5]. linear spring-loaded probe in a variable magnetic
Accordingly, ultra-thin pinned layers have, in addi- field. An electromagnet and power supply provide
tion to reduced demagnetizing effects, the added the applied field and all measurements are made at
advantage of improved spin-valve performance in room temperature.
terms of linearity. In this study, we fabricate (mac-
roscopic) FeMn-based spin-valves with ultra-thin
pinned layers using three different materials 3. Experimental results
systems, CoNiFe/Cu, NiFe/Cu, and CoFe/Cu to
determine whether enhanced Hp values are sus- MR versus applied field curves are shown in
tained as pinned-layer thicknesses are reduced Fig. 1 for a spin-valve fabricated with CoNiFe as
to one or two atomic layers. the magnetic material. For this particular set of
data, the pinned layer is 0.5, 1.5 and 3.0nm, in
Fig. la-Fig, lc, respectively. The relationship be-
2. Experimental techniques tween/-/p and pinned-layer thickness is shown in
Fig. 2 for all material systems. It is clear that Hp is
Spin-valves are fabricated by DC magnetron inversely related to pinned-layer thickness with
sputter deposition on Corning 7059 glass slides Hp approaching 800-900 Oe for ultra-thin (~0.5 nm)
(2 x 2 in2). The Vac-Tec Model 250 sputtering sys- magnetic pinned layers. In previous work, we
tem is located in a Class-1000 clean room. have observed a further increase in Hp when
Predeposition base pressure of the system is less the spin-valves are slow-annealed at (~60°C)
than 2 x 10 -7 Torr and samples are deposited un- for extended periods of time [8]. The largest
der an Argon pressure of ~ 5.0 mTorr. Films are increase in pinning field is observed when the
deposited at ambient temperature with an aligning as-deposited pinning field is high. Structures
field of 80 Oe parallel to the substrate surface dur- enhanced in all spin-valves used in our current
ing deposition. Sputtering rates are calculated from study: However, the magnitude of G M R is compro-
thickness measurements of the reference films made mised somewhat for these samples as shown in
3. S.L. Burke# et al. / Journal of Magnetism and Magnetic Materials 168 (1997) L233-L236 L235
1000
• CoNiFe
900
• CoFe
• NiFe
800
3
700
600
2
o 50O
1
400
300
0 6 •
-1000 -800 -600 -400 -200 200
2O0
(a ) F.xteman ~eld (Oe)
100
0 I I I [ ]
0.0 0.5 1,0 1.5 2,0 2.5 3.0
_f
Pinned Layer Thickness (nm)
3.
Fig. 2. Pinning field versus pinned-layer thickness.
i
2-
1- • CoNiFe
• CoFe
A NJFe
0
-lo00 -8OO -6O0 400 -~0 200
(b) e.,a,,',mn v i ~ (c~)
n"
(.9
1
0 0.0 0.5 1,0 1.5 2.0 2.5 3.0
o1000 400 -600 -400 -200 0 200
P i n n e d L a y e r T h i c k n e s s (nm)
(c) Exlemal Field (Oe)
Fig. 3. G M R versus pinned-layer thickness.
Fig. 1. G M R versus applied field.
less dependence on pinned-layer thickness with
Fig. 3. G M R for CoNiFe and CoFe material sys- magnitudes ranging from 1.5-2.2% for a corre-
tems decrease from 3 - 4 % to less than 2% when the sponding thickness range of 0.8-2.0 nm.
pinned layer is below approximately 0.8 nm. G M R Coercivity (He) is also monitored for these
in spin-valves utilizing NiFe films appear to exhibit spin-valves. Fig. 4 shows Hp/Hc versus pinned
4. LETTER TO THE EDITOR
L236 S.L. Burkett et al. / Journal o f Magnetism and Magnetic Materials 168 (1997) L233-L236
60 (~0.5 nm). Measured values for H p range from
800-900 Oe in CoNiFe/Cu and CoFe/Cu multi-
• CoNiFe
• CoFe layer material systems and approximately 500 Oe is
50 • NiFe obtained in NiFe/Cu multilayers. Current research
efforts are focused on studying the uniformity and
40 microstructure of ultra-thin pinned layers, as well
as different annealing schemes for investigating
thermal stability in these materials.
3O
"1-
20 Acknowledgements
This research was supported in part by NSF
10
MRSEC Cooperative Agreement No. DMR-
9400399. The authors would like to thank Profes-
I I [ I I sor H. Fujiwara for valuable discussions. One of us
0.0 0.5 1.0 1.5 2.0 2.5 3.0 (M.R.P) would like to acknowledge the support
Pinned Layer Thickness (nm) for this work through a research grant from JVC
Corporation.
Fig. 4. Hp/H c versus pinned-layer thickness.
layer thickness for the three multilayer material References
systems. It is well-established that Hp/Hc>> 1 is
a prerequisite for pinned-layer spins returning to [1] J.C.S. Kools, IEEE Trans. Magn. 32 (1996) 3165.
a well-defined quiescent state immediately follow- [2] H.N. Bertram, Theory of Magnetic Recording (Cambridge
ing magnetic excitation [9]. Finally, one intriguing University Press, Cambridge, 1994).
[3] T.R. Koehler and M.L. Williams, IEEE Trans. Magn. 32
aspect of Fig. 1 deserves mention. In spin-valves (1996) 3446.
with ultra-thin pinned layers, the coercivity of the [4] Y. Hamakawa, H. Hoshiya, T. Kawabe, Y. Suzuki, R. Arai,
free layer appears to fall to values less than those K. Nakamoto, M. Fuyama and Yi Sugita, IEEE Trans.
observed in conventional designs. Fujiwara [10] Magn. 32 (1996) 149.
has suggested that reduced magnetostatic coupling [5] Y.K. Kim, K. Ha and L.L. Rea, IEEE Trans. Magn. 31
(1995) 3823.
in ultra-thin pinned layers could account for this. [6] Y. Kitade, H. Kikuchi, H. Kishi, M. Otagiri and K.
This particular aspect is being investigated further. Kobayashi, IEEE Trans. Magn. 31 (1995) 2600.
[7] K. Nishioka, T. Iseki, H. Fnjiwara and M.R. Parker,
J. Appl. Phys. 79 (1996) 4970.
4. Conclusions [8] S i . Burkett, S. Kora, J.C. Lusth and M.R. Parker, IEEE
Trans. Magn., submitted.
[9] T. Lin, C. Tsang, R.E. Fontana and J.K. Howard, IEEE
Enhanced exchange pinning field is observed in Trans. Magn. 31 (1995) 2585.
FeMn spin-valves with ultra-thin pinned layers [10] H. Fujiwara, private communication.