Hello, I am Subhajit Pramanick. I and my classmate, Anannya Sahaw, both presented this ppt in seminar of our Institute, Indian Institute of Technology, Kharagpur. The topic of this presentation is on exchange interaction and their consequences. It includes the basic of exchange interaction, the origin of it, classification of it and their discussions etc. We hope you will all enjoy by reading this presentation. Thank you.
Basic operating principle and instrumentation of photo-luminescence technique. Brief description about interpretation of a photo-luminescence spectrum. Applications, advantages and disadvantages of photo-luminescence.
Basic operating principle and instrumentation of photo-luminescence technique. Brief description about interpretation of a photo-luminescence spectrum. Applications, advantages and disadvantages of photo-luminescence.
weiss molecular theory of ferromagnetismsantoshkhute
Weiss' Theory (Domain theory of ferromag : According to weiss, a feromagnetic substance. contains atoms with permanent magnetic. moments, as in a paramagnetic substance, but due to special form of interaction.
It contains the basic principle of Mossbauer Spectroscopy.
Recoil energy, Dopler shift.
The instrumentation of Mossbauer Spectroscopy.
Hyperfine interactions.
Where possible- give definitions-explanations for each of the followin.docxSUKHI5
Where possible, give definitions/explanations for each of the following. If not possible
explain what is wrong with the terminology.
(a) Ferromagnetism and ferromagnetically coupled – and the distinction between the two
terms.
(b) Antiferromagnetism and antiferromagnetically coupled – and the distinction between
the two terms.
(c) Ferrimagnetism and ferrimagnetically coupled – and the distinction between the two
terms.
Solution
Ferromagnetism -
Electron has a magnetic dipole moment, i.e., it behaves like a tiny magnet, producing a magnetic field. Due to its quantum nature, the spin of the electron can be in one of only two states; with the magnetic field either pointing \"up\" or \"down\". When these magnetic dipoles in a piece of matter are aligned, (point in the same direction) their individually tiny magnetic fields add together to create a much larger macroscopic field resulting in large net magnetization even in the absence of a magnetic field.
Ferromagnetically coupled -
The term us used in the explanation of molecular magnetic interactions. If in a molecule there exist two interacting magnetic centers (eg. two Cu2+ ions in direct interaction or bridged a ligand). The two election can be aligned in same direction in the molecule, resulting a higher magnetic moment - termed as ferromagnetically coupled metal centers. The interaction is termed as ferromagnetic coupling.
Antiferromagnetism -
It is the opposite of ferromagnetism in which the magnetic elections are aligned anti-parallel resulting very low or zero net magnetization.
Antiferromagnetically coupled -
Opposite to ferromagnetically coupled, in which the elections in the two magnetic centers are aligned anti-parallel to each other, resulting in lower magnetic moment for the compound.
Ferrimagnetism -
It a crystal, the lattice are composed of multiple sub lattices, and if a magnetic ion is located in a sub lattice and which is interacting with other magnetic centers in nearby sub lattice by indirect or superexchange interactions, results in anti-parallel alignment of spins between two sub lattice. If the interactions are not cancelled each other, results a net magnetic moment. The phenomena is known as ferrimagnetism.
Ferrimagnetically coupled,-
The coupling interaction on spin centers in a crystal of a inorganic molecule, are coupled each other and resulting to a net magnetic moment- in known as ferrimagnetically coupled.
.
weiss molecular theory of ferromagnetismsantoshkhute
Weiss' Theory (Domain theory of ferromag : According to weiss, a feromagnetic substance. contains atoms with permanent magnetic. moments, as in a paramagnetic substance, but due to special form of interaction.
It contains the basic principle of Mossbauer Spectroscopy.
Recoil energy, Dopler shift.
The instrumentation of Mossbauer Spectroscopy.
Hyperfine interactions.
Where possible- give definitions-explanations for each of the followin.docxSUKHI5
Where possible, give definitions/explanations for each of the following. If not possible
explain what is wrong with the terminology.
(a) Ferromagnetism and ferromagnetically coupled – and the distinction between the two
terms.
(b) Antiferromagnetism and antiferromagnetically coupled – and the distinction between
the two terms.
(c) Ferrimagnetism and ferrimagnetically coupled – and the distinction between the two
terms.
Solution
Ferromagnetism -
Electron has a magnetic dipole moment, i.e., it behaves like a tiny magnet, producing a magnetic field. Due to its quantum nature, the spin of the electron can be in one of only two states; with the magnetic field either pointing \"up\" or \"down\". When these magnetic dipoles in a piece of matter are aligned, (point in the same direction) their individually tiny magnetic fields add together to create a much larger macroscopic field resulting in large net magnetization even in the absence of a magnetic field.
Ferromagnetically coupled -
The term us used in the explanation of molecular magnetic interactions. If in a molecule there exist two interacting magnetic centers (eg. two Cu2+ ions in direct interaction or bridged a ligand). The two election can be aligned in same direction in the molecule, resulting a higher magnetic moment - termed as ferromagnetically coupled metal centers. The interaction is termed as ferromagnetic coupling.
Antiferromagnetism -
It is the opposite of ferromagnetism in which the magnetic elections are aligned anti-parallel resulting very low or zero net magnetization.
Antiferromagnetically coupled -
Opposite to ferromagnetically coupled, in which the elections in the two magnetic centers are aligned anti-parallel to each other, resulting in lower magnetic moment for the compound.
Ferrimagnetism -
It a crystal, the lattice are composed of multiple sub lattices, and if a magnetic ion is located in a sub lattice and which is interacting with other magnetic centers in nearby sub lattice by indirect or superexchange interactions, results in anti-parallel alignment of spins between two sub lattice. If the interactions are not cancelled each other, results a net magnetic moment. The phenomena is known as ferrimagnetism.
Ferrimagnetically coupled,-
The coupling interaction on spin centers in a crystal of a inorganic molecule, are coupled each other and resulting to a net magnetic moment- in known as ferrimagnetically coupled.
.
FERROMAGNETIC-FERROELECTRIC COMPOSITE 1D NANOSTRUCTURE IN THE PURSUIT OF MAGN...ijrap
Nanocomposites of linear chain of ferroelectric-ferromagnetic crystal structure is considered. It is analyzed
theoretically in the motion equation method on the pursuit of magnonic excitations,lattice vibration
excitations and their interactions leading to a new collective mode of excitations,the electormagnons. In
this particular work, it is observed that the magnetizations and polarizations are tunable in a given temperature ranges for some specific values of the coupling order parameter.
Ferromagnetic-Ferroelectric Composite 1D Nanostructure in the Pursuit of Magn...ijrap
Nanocomposites of linear chain of ferroelectric-ferromagnetic crystal structure is considered. It is analyzed
theoretically in the motion equation method on the pursuit of magnonic excitations,lattice vibration
excitations and their interactions leading to a new collective mode of excitations,the electormagnons. In
this particular work, it is observed that the magnetizations and polarizations are tunable in a given
temperature ranges for some specific values of the coupling order parameter
The present article gives the fundamental properties magnetism, different materials, properties of different magnetic materials like, dia,para and ferro magnetic materials. The notes also explain how magnetism appear in materials, type of magnets and brief applications of magnetic materials. The materials is best for undergraduate science and engineering students and any other people of interest in magnetism
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Unveiling the Energy Potential of Marshmallow Deposits.pdf
Exchange Interaction and their Consequences.pptx
1. Topic: - Exchange Interactions and Their Consequences
Presented by :-
Name – Subhajit Pramanick
Roll No – 22PH91R16
Department of Physics
IIT Kharagpur
Name – Anannya Sahaw
Roll No – 22CY91R01
Department of Chemistry
IIT Kharagpur
2. Contents
What is Exchange Interaction?
Origin of Exchange Interaction
Classification of Exchange Interaction
Direct Exchange
Indirect Exchange
Super Exchange
RKKY Exchange
Double Exchange
Anisotropic Exchange Interaction
3. What is Exchange Interaction?
Purely QM effect, occurs only between identical
particles.
Boson and fermion both can experience it. For
fermions, it is Pauli repulsion, related to Pauli
exclusion principle whereas for bosons, it is one
type of effective attraction which makes them
close to each other, as in Bose-Einstein
Condensation.
In case of two fermions, if they are parallel, they
remain far apart (Pauli Exclusion Principle) whereas
if they are antiparallel, they may come closer
together such that their wave functions may overlap
(see figure).
Charges of same sign cost energy when they are
close together and save energy when they are far
apart.
4. Origin of Exchange Interaction
f
Consider a simple model with just two electrons (𝐬𝟏= 𝐬𝟐=
𝟏
𝟐
).
So, total spin, S =
1
2
−
1
2
, (
1
2
+
1
2
) = 0 (singlet),1 (triplet)
Singlet State :
S = 0. So, 𝐦𝐬 = 0 → only one state
Total wave function, 𝚿𝐬 = 𝛗𝐬 𝛘𝐬
𝛗𝐬 →symmetric, 𝛘𝐬 →antisymmetric (since 𝚿𝐬 →antisymmetric).
Here, 𝛗𝐬 =
𝟏
𝟐
[ 𝝋𝒂(𝑟𝑎) 𝝋𝒃(𝑟𝑏) + 𝝋𝒂(𝑟𝑏) 𝝋𝒃(𝑟𝑎) ] and
𝛘𝐬 =
𝟏
𝟐
[ ↑ ↓ - ↓ ↑ ]
Energy: 𝐄𝐒 = 𝚿𝐬
∗
𝐇 𝚿𝐬 d𝐫𝟏 d𝐫𝟐 and 𝐬𝟏.𝐬𝟐 = -
𝟑
𝟒
Triplet States :
S = 1. So, 𝐦𝐬 = -1,0,+1 → total three states
Total wave function, 𝚿𝐓 = 𝛗𝐓 𝛘𝐓
𝛗𝐓 →antisymmetric, 𝛘𝐓 →symmetric (since 𝚿𝐓 →antisymmetric).
Here, 𝛗𝐓 =
𝟏
𝟐
[ 𝝋𝒂(𝑟𝑎) 𝝋𝒃(𝑟𝑏) - 𝝋𝒂(𝑟𝑏) 𝝋𝒃(𝑟𝑎) ] and
𝛘𝐓 = ↑ ↑ , ↓ ↓ ,
𝟏
𝟐
[ ↑ ↓ + ↓ ↑ ]
Energy: 𝐄𝐓 = 𝚿𝐓
∗
𝐇 𝚿𝐓 d𝐫𝟏 d𝐫𝟐 and 𝐬𝟏.𝐬𝟐 =
𝟏
𝟒
5. Origin of Exchange Interaction
So, 𝐄𝐒 - 𝐄𝐓 = 2 𝝋𝒂
∗
(𝒓𝒂) 𝝋𝒃
∗
(𝑟𝑏) 𝐇 𝝋𝒂(𝒓𝒃) 𝝋𝒃(𝑟𝑎) d𝐫𝟏 d𝐫𝟐
Now, Hamiltonian can be written as : 𝐇 =
𝟏
𝟒
(𝐄𝐒 + 3𝐄𝐓) – (𝐄𝐒 - 𝐄𝐓) 𝐬𝟏.𝐬𝟐
Define, Exchange Integral:
J =
𝐄𝐒 − 𝐄𝐓
𝟐
= 𝝋𝒂
∗
(𝒓𝒂) 𝝋𝒃
∗
(𝑟𝑏) 𝐇 𝝋𝒂(𝒓𝒃) 𝝋𝒃(𝑟𝑎) d𝐫𝟏 d𝐫𝟐
So, the spin-dependent term in the Hamiltonian becomes:
𝐇𝒔𝒑𝒊𝒏 = - 2J 𝐬𝟏.𝐬𝟐
This term in the Hamiltonian is the origin of exchange interaction
between two identical particles.
If J>0, 𝐄𝐒> 𝐄𝐓 then triplet state S=1 is favoured (Ferromagnetism). If J<0, 𝐄𝐒<𝐄𝐓
then singlet state S=0 is favoured (Anti-ferromagnetism).
In many electron system for ferromagnetism or anti-ferromagnetism, considering
exchange interaction Heisenberg gave the simplest model in which,
𝐇 = - 𝐢𝐣 𝐉𝐢𝐣 𝐬𝐢 . 𝐬𝐣 or 𝐇 = - 2 𝐢>𝐣 𝐉𝐢𝐣 𝐬𝐢 . 𝐬𝐣
sometimes, 𝐇 = - 𝐢𝐣 𝐉𝐢𝐣 𝐬𝐢 . 𝐬𝐣
more simply, 𝐇 = - J 𝐢𝐣 𝐬𝐢 . 𝐬𝐣
6. Classification of Exchange Interaction
Exchange
Interaction
Direct
Exchange
Indirect
Exchange
Super
Exchange
RKKY
Exchange
There are mainly two types of exchange interactions:
Besides this, there are many other exchange interactions like: Double Exchange interaction, Anisotropic
Exchange Interaction etc.
7. Direct Exchange
Electrons of neighbouring magnetic atoms interact via
an exchange interaction. It don’t need any intermediary.
Direct interaction between neighbouring atoms is due to the
spatial overlap of orbitals.
The simplest model for this kind of interactions is the
Heisenberg model: 𝐇 = - J 𝐢𝐣 𝐬𝐢 . 𝐬𝐣
Depending on J values some of the metals are FM
and some are AFM (see, Bethe-Slater Curve).
Very often direct exchange cannot be an important
mechanism in controlling the magnetic properties because
there is insufficient direct overlap between neighbouring
magnetic orbitals as in case of rare earths and transition
metals. Then it becomes necessary to consider indirect
exchange.
Bethe-Slater Curve
8. Indirect Exchange
It is the coupling between magnetic moments over long distance and requires a mediator.
It can be of two types (a) Super Exchange (b) RKKY Exchange
Indirect Exchange in Ionic Solid: Super Exchange
In systems in which direct exchange cannot be realized due to insufficient overlap of magnetic orbitals,
magnetic coupling may be mediated by orbitals of a nonmagnetic ligand in between them. It is the super
exchange interaction, which is responsible for the magnetic properties of the most of magnetic materials,
especially nonmetallic compounds, for example, oxides or fluorides. Generally found in metal oxides
where the magnetic atoms are separated by non magnetic ions ( O2- ).
9. Superexchange depends on the electron configuration of magnetic ions and 𝐌𝟏–O–𝐌𝟐 bond angle. The
rules given by Goodenough, Kanamori, and Anderson help us to predict the resulting coupling:
Indirect Exchange
Goodenough-Kanamori rules
Strong negative coupling when 𝐌𝟏–O–𝐌𝟐 angle
is equal to 180o: There is a strong
antiferromagnetic exchange interaction if the
half-filled orbitals of two cations overlap with
the same empty or filled orbital of the
intervening anion.
Weak positive coupling when 𝐌𝟏–O–𝐌𝟐 angle is
equal 90o : There is a weaker ferromagnetic
exchange interaction if the half-filled orbitals of
two cations overlap with orthogonal orbitals of
the same intervening anion.
10. Indirect Exchange
Indirect Exchange in Metal: RKKY or Itinerant Exchange
Another type of indirect exchange is active in metals, where
conduction electrons may mediate the interaction between
localized magnetic moments of metal ions known as
(Ruderman, Kittel, Kasuya, and Yosida interaction) or RKKY
exchange.
This type of coupling applies mainly to lanthanides based
materials, in which the 4f shells are localized close to the
nucleus. The 4f moments polarize spins of the 5d or 6s electrons
and this polarization is transferred to the moment of the
adjacent metal ion.
The RKKY mechanism depends on a density of states of
conduction electrons and works on a long range.
Exchange integral, JRKKY ∝
𝐜𝐨𝐬(𝟐𝑲𝑭 𝒓)
𝒓𝟑
Depending upon the distance between the localized
moments of two magnetic ions, it may be either FM or
AFM.
11. Double Exchange
In compounds in which magnetic ion occurs in two oxidation states (mixed valency), for example Fe2+
and Fe3+ or Mn3+ and Mn4+, magnetic coupling may be realized by means of a real electron delocalization
to the empty orbital of the neighbour.
The hopping of an extra electron of Fe2+ or of Mn3+ via the 2p orbital of oxygen proceeds without the
spin-flip of the hopping electron and results in the ferromagnetic coupling of the two centers. The
double exchange operates in Fe3O4, La1−x SrxMnO3.
12. Anisotropic Exchange Interaction
This is also known as Dzyaloshinsky-Moriya (D-M) interaction. Here spin-orbit
interaction plays the role as the oxygen atoms act in super exchange.
The excited state is produced by the spin-orbit interaction in one of the
magnetic ions and an exchange interaction occurs between excited state of one
ion and ground state of other ion.
This interaction includes a term in the Hamiltonian, 𝐇𝑫𝑴 = 𝐃. 𝐬𝟏 × 𝐬𝟐
𝐃 will lie parallel or perpendicular to the line connecting two spins,
depending on the symmetry.
This interaction is such that it tries to force 𝐬𝟏 and 𝐬𝟐 to be at right angles in a
plane perpendicular to 𝐃 in such an orientation as to ensure that energy is
negative. Its effect is therefore very often cant the spins by small angle.
For this spin canting, antiferromagnetic materials show some non-zero
magnetic moment near absolute zero (Weak Ferrimagnetism).