Jornada Científica NanoFront Mag - 21 de junio de 2016 - IMDEA Nanociencia GMM-CSIC Manuel Vázquez

1. MAGNETIC NANO & MICRO WIRES
Manuel Vazquez
Group of Magnetic Wires
.
Institute of Materials Science of Madrid, CSIC. Spain
1.5 mm metallic diameter

2. AUTOR/ES TÍTULO FECHA TIPO REVISTA CAPÍTULO PÁGINAS COMENTARIO
C. Bran, E.M. Palmero, Zi-An Li, R.P.
del Real, M Spasova, M Farle and M
Vázquez
Correlation between structure and magnetic
properties in CoxFe100-x nanowires: the
roles of composition and wire diameter
2015 Article J. Phys. D: Appl. Phys. 48 145304 (7pp)
Col. Duisburg-Essen
Univ.
C. Bran, A.P. Espejo, E.M. Palmero, J.
Escrig and M. Vázquez
Angular dependence of coercivity with
temperature in Co-based Nanowires
2015 Article
J. Magn. Magn.
Mater.
396 327–332
Col. Santiago Chile
Univ.
J.G. Ovejero, C. Bran, M.P. Morales
and M. Vazquez
Electrochemical synthesis of core–shell
magnetic nanowires
2015 Article J. Magn.Magn. Mater. 389 144–147 Letter to the Editor
Belén Sanz, Ester M. Palmero, Rafael
P. del Real, Manuel Vázquez and
Carmen Mijangos
Arrays of Magnetic Ni Nanowires Grown
Inside Polystyrene Nanotubes
2015 Article Ind. Eng. Chem. Res. 54 13005−13008 Coll. ICPM/CSIC
M. Vazquez, R. ElKammouni, G.V.
Kurlyandskaya, V. Rodionova and L.
Kraus
Bimagnetic Microwires, Magnetic Properties
and High-Frequency Behavior
2016 Book Chapter
“Novel Functional
Magnetic Materials”,
A. Zhukov (ed.)
7 29 pag.
Springer Series in
Materials Science
231, DOI
10.1007/978-3-319-
26106-5_7, Springer
International
Publishing
Switzerland) 2016
M.S. Arshad, M.P. Proença, S.
Trafela, V. Neu, U. Wolff, S. Stienen,
M. Vazquez, S. Kobe and K.Ž.
Rožman
An oblivious growth mechanism for high-
magnetic-anisotropy hcp Co-Pt nanowire
arrays: the role of the crystal orientation in
the switching-field distribution and the
magnetic-domain configuration
2016 Article J. Phys. D: Appl. Phys.
in the press Coll.
Slovenia Univ
Alejandro Jiménez, Peter Klein,
Rastislav Varga, Rafael Pérez and
Manuel Vázquez
On the induced voltage by the domain wall
propagation in cylindrical magnetic
microwire
2016 Article IEEE Magn Letters
Submittted Coll.
Kosiçe Univ
M P Proenca, C T Sousa, J Ventura, J
Garcia, MVazquez and J P Araujo
Identifying less-interacting single domain
states in Ninanowire arrays by FORC
2016 Article J. Phys. D: Appl. Phys.
Submitted; Coll.
Porto Univ.
Lei Shao,Yangyong Zhao, Alejandro
Jiménez, Manuel Vázquez, Yong
Zhang
Shape memory and huge superelasticity in
Ni-Mn-Ga microwires
2016 Article Metals
Submmitted; Col.
University of
Science and
Technology Beijing

3. AUTOR/ES TÍTULO TIPO CONFERENCE FECHA LUGAR
A. Jimenez, R.
Varga and M.
Vazquez
Electromotive force indiced by
domain wall propagation in
magnetic microwire
Oral
Presentation
INTERMAG'2015 13/05/2015 Beijing, China
M. Vázquez, C.
Bran, A. Asenjo, R.
Perez, E. Palmero,
Y. Ivanov and O.
Chubykalo-Fesenko
On the magnetization reversal of
Co based nanowires
Invited
Presentation
Int. Worksh. Magnetic
Nanowire and
Nanotubes
19/05/2015
Meersburg,
Germany
A. Jimenez, R.
Varga, R. Perez and
M. Vazquez
Controlled motion of single
Domain Walls in magnetic
microwires
Invited
Presentation
7th
Int. Workshop on
Magnetic Wires
02/07/2015 Ordizia, Spain
M. Vazquez
Program
Committee
Chair
International Conf. on
Magnetism, ICM
5-10 / 07 /
2015
Barcelona, Spain
C. Bran, E. Palmero,
E. Berganza, R.P. del
Real, A. Asenjo and
M. Vazquez
Co-based cylindrical nanowires:
from applications of their arrays to
the spin reversal of individual
nanowires
Invited
Presentation
NanoPyme Workshop
on Rare-earth free
permanent magnets
and applications
14/09/2015 Madrid
M. Vazquez, C.
Bran, E. Palmero, E.
Berganza, R.P. del
Real, A. Asenjo
Magnetization reversal of Co and
CoFe-based cylindrical nanowires
Invited
Presentation
Amorphous and
Nanostructured
Magnetic Materials,
ANMM’15
23/09/2015 Iasi, Romania
R. Perez, E.M.
Palmero, C. Bran
and M. Vazquez
Magnetic nanowires used in
magnetic pick-up senswors
Oral
Presentation
2016
MMM/INTERMAG
Conf.
12/01/2016 San Diego, USA
M. Vazquez
CoFe based nanowires and their
technological applications
Inaugural
Invited Talk
3rd. Int. Conf. on
Recent Trends in
Physics, ICRTP,
13/02/2016 Indore, India

4. AUTOR/ES TÍTULO FECHA
TIPO
PUBLICACIÓN
DIRECTOR/
ES COMENTARIO
Rhimou El
Kammouni
Single and Biphase Magnetic
Microwires: Microwave
behavior and temperature
dependence
2015 (Abril) PhD Thesis, UAM M. Vazquez
Tutor: M.A.
Ramos
Sobresaliente
cum laude
unanimidad
Alejandro
Jimenez Villada
Dinámica de la propagación de
una única pared de dominio y
procesos de imanación en
microhilos magnéticos
2016 (22
Enero)
PhD Thesis, UAM M. Vazquez
Tutor: M.
Hernández-
Vélez
Sobresaliente
cum laude
unanimidad
Ester M.
Rodriguez
Palmero
2016
(Noviembre)
M. Vazquez
& R. Perez
Joe Angel
Fernandez
2018 (Mayo)
M.Vazquez
& R. Perez
& O.
Chubykalo

5. MAGNETIC NANO & MICRO WIRES
1.- Magnetic Nanowires:
Synthesis of CoFe with controlled anisotropy
Nanowires with modulated diameter & Core/shell nanowires
2.- Magnetic Mcrowires:
FMR in biphase microwires
Controlled motion of single Domain-Wall in single phase microwires
1.5 mm metallic diameter

6. -Looking for specific cylindrical nanowires & arrays
- Arrays ar relevant for 3D magnetic architectures,
sensor devices, novel magnets, biomagnetic
functionalization and beyond
- Individual nanowires are nearly ideal systems for
fundamental studies on magnetization & reversal
- Why Electrochemical route of fabrication?
Less-expensive technique
Ability to grow various cylindrical nanowires with
designed geometry and composition periodical modulations
- Why cylindrical symmetry nanowires?
Nanoscale systems profiting of strong shape anisotropy
(Diameter: 15nm to 200nm; Length: 100nm to 50mm)
Nanocolumns,Nanotubes,Multilayer,Diameter-Modulated, Core@Shell
- Combining magnetic (Co, Fe) elements & alloys
to tailor structure and magnetocrystalline anisotropy so
magnetic response
Designed Cylindrical Nanowires: Overall Motivation
Self-assembled pore
template
CoFe nanowire array

7. 1.- Uniform/straight Nanowires:
Nanodots, Nanowires (reduced diameter)
2.- Modulated Nanowires :
a) Longitudinal
Multisegmented, Multilayer
b) Radial
Nanotubes, Core/Shell
c) Diameter Modulated
Co/Cu
multisegmented
Ni
nanotubes Fe&Au core&shell
CoFe diameter
modulated
Families of magnetic nanowires
prepared by electrochemical route at ICMM/CSIC, Madrid
CoFe homogneous

8. Removal of
alumina
Au layer sputtering
NWs
growth
Removal of
barrier layer
Al foil
Removal of
Al layer
1st
anodization
2nd
anodization
Potentiostatic
electrodeposition
Synthesis procedure: AAO template + metals electroplating
Al disk and inner
electroplated region
NWs released from
the membrane
Anodic Aluminium Oxide,
AAO, membrane
FeCo NWs

9. Correlation Magnetic to Structure characterizatics
FeCo alloy
nanowires
40nm diam.
20 nm diam.
For 40 nm wires, structure evolves from bcc to fcc as the Co% increases
For 20 nm wires, it evolves as bcc->fcc->hcp
Role of Composition and Nanowire Diameter

10. HRTEM characterisation of individual Co nanowires
Single crystal [111] fcc
Co nanorod
X.X. Zhang, KAUST
Single crystal hcp
Co nanorod

11. fixed diameter, D=35nm and length, L=3mm
Textured along different directions in
hcp-phases with pH of synthesis
Co nanowires: Crystal structure and Magnetic Anisotropy

12. TEM study of Co nanowires prepared under different electrolyte pH:
(a) – pH 3.5, (b) - pH 5.0, (c) – pH 6.0
The insets show the corresponding electron diffraction patterns and HRTEM images
The green arrows show the orientation of the c-axis.
The white arrows indicate the crystal orientation
Co nanowires: Crystal structure and Magnetic Anisotropy
Yu.P. Ivanov et al. Nanotechnology 2014

13. Hysteresis loops & Spin imaging: VSM & SQUID vs. VF-MFM & MTXM
-100 -80 -60 -40 -20 0 20 40 60 80 100
-1.0
-0.5
0.0
0.5
1.0
Mr/Ms
B(mT)
Ciclo SQUID
Ciclo MFM
MFM imaging of Ni nanowires
(d=180 nm, L = 2 mm)
A. Asenjo et al. PRB 2007
Vazquez et al. Eur.J. Phys. 2005
-3000 -2000 -1000 0 1000 2000 3000
-1.0
-0.5
0.0
0.5
1.0
M/MS
Magnetic Field (Oe)
H paralelo
diámetro 35nm
VSM
loop

14. LorTEM images in over- (a) and under-focused (b)
conditions of an array Co NWs 45 nm in diameter
and 55-nm long at remanence.
The arrows show the transverse direction and the
clockwise (red) and anticlockwise (blue) rotation of
NW magnetization.
As schematically shown on (c), the magnetic vortex
acts as a convex or a concave lens, depending on its
chirality, which creates a focus above or below the
sample. Looking at these planes, we detect uniquely
the presence of a vortex state and determine its
chirality.
On the hologram image (d) the high- and low-phase
values are represented by two different color
sequences that correspond to the clockwise and
anticlockwise rotation of NW magnetization and (e)
shows the contour lines corresponding to the B┴.
Lorentz microscopy & electron holography: Co nanowires
Electron holography directly measures the phase shift of
the electron wave passing through the sample by measuring
the phase shifts on the interferogramIvanov et al.
(Submt. Sc. Reports)

15. Coercivity Hc as a function of NW
diameter for single crystal hcp Co NWs
and different easy axis orientations
(defined by the angle θ with NW axis)
Modeling: role of diameter & crystal symmetry
hcp Co nanowires (2 mm long)
Changing the reversal mode with
Anisotropy easy axis
Regions (1), (2), (3) correspond
to applied fields at which a
vortex is formed, at the
remanence, and when the
vortex core is switched

16. Uniform
Alloy NW
Multisegmented
in composition
Modulated
in diameter
Individual FeCoCu Nanowires:
artifially designed to control the reversal process
MFM image of
uniform alloy Nanowire

17. Grown inside Hard-Mild pulsed anodized templates
Growing nanowires with modulated diameter (Co & CoFe)
Co nanowires
Fine control over shape of nanopores
is hard to achieve

18. Diagram with two
types of modulations
Kerr effect in individual modulated nanowires (Fe27Co68Cu5)
The presence of single and several Barkhausen
jumps are detected depending on geometry
E. Palmero, C. Bran et al Nanotechnology (2015)
D1=150nm
D1=150nm, L1=800nm
D2=170nm, L2= 50 nm
D1=130nm, L1=1000nm
D2=100nm, L2= 300 nm
D1=150nm, L1=800nm
D2=170nm, L2= 50 nm

19. AxialprofileofKerrloops
Angular dependence of Coercivity
Local MOKE loops
along the nanowires
Fitting to vortex-like
DW propagation mode

20. SEM images of modulated FeCoCu wires dispersed on Si substrate.
FeCo modulated nanowires show bcc structure with a (110) orientation.
Due to the small magnetocrystalline anisotropy, shape anisotropy, dominates
Co nanowires show hcp structure with c-axis nearly perpendicular,
magnetocrystalline anisotropy dominates
FeCoCu & Co modulated (bamboo-like) nanowires

21. FeCo MFM imaging: uniform vs. modulated nanowires

22. PEEM –XMCD results
XMCD contrast in a single FeCoCu modulated nanowire.
- Direct photoemission (magnetic contrast from the top few nm, surface information)
- Transmission data (shadow, x-rays partially transmitted through the wires, bulk information)
FeCoCu & Co bamboo-like modulated nanowires
XMCD images of CoFe and Co nanowires are
recorded at the Fe and Co L3 and L2 edges reversing
the photon helicity using the PEEM end-station
Synchrotron
Light Facility, Barcelona

23. Co nanowires
Axial anisotropy Perpendicular anisotropy
Axial spins at the core
Vortex at the end
FeCoCu nanowires
PEEM –XMCD in bamboo-like modulated nanowires:
information on surface and bulk spin configuration
MFM
MFM

24. Remanent spin configurations of
(a) FeCoCu and (b) Co bamboo
nanowires
A half wire length is shown (1
micron) containing an edge and two
modulations marked by the green
arrows.
Inserts show the transversal cross
sections at the marked regions along
the length:
Black arrows denote the spin
orientation in the corresponding
section
Red-White-Blue color contrast at
background corresponds to axial
magnetization.
J.A. Fdez-Roldán, mumag code
Simulations in CoFeCu and Co bamboo-like Nanowires at Remanence

25. Multisegmented nanowires: Structural data [FeCoCu/Cu]n
TEM images of FeCoCu(300 nm)/Cu(15 nm) nanowires: (a) Bright field image of an individual nanowire, (b) HRTEM
image of a Cu spacer, (c) and d) Fast Fourier Transform at Cu and FeCoCu regions of the HRTEM image
Cu layers perfectly segregated
from the FeCoCu; irregular and
rough->the polycrystalline nature
of the wires, the large grain size
and inhomogeneities in the
growth.

26. Proenca et al, Phys. Rev. B, 2013
Exchange coupling through oxidation of the inner walls
Core–Shell magnetic nanowires as new class of systems with
composition and microstructure radial profile
.
Core/Shell nanowires & nanotubes at ICMM/CSIC
Ni –Polystere core/shell nanowires
Alumina Membrane + PVA + Fe3O4 Mijangos et al, (I&EC research 2016)
Martin et al, J Nanosci.Nanotechn 2010
Magneto-polymeric
hybrid systems
Fe/Fe3O4
core/shell
nanowire

27. Growing of Nanotube and Core@Shell Nanowire Arrays
Nanotubes: Single Electrodeposition
Core@Shell: Double Electrodeposition

29. 500 nm
Outer diameter ~ 300 nm
Wall thickness ~ 30 nm
Length ~ 15 mm 500 nm
FESEM
Controlled production of ordered arrays of Ni nanotubes
Outer diameter ~ 50 nm
Wall thickness ~ 10 nm
Length ~ 50 mm
50 nm diameter
10 nm wall thickness
50 mm length
105 nm intertube distance

30. Empty AAO membrane (a),
Au nanotubes (b),
TM@Au core/shell nanowires (c),
contact removed TM@Au nanowires
prepared for releasing (d).
Fe@Au core/shell nanowires:
Au grown under different potentials:
0.35 (a), 0.8 (b), 1.0 (c) and 1.25V (d)
Two-step electrodeposition process
to obtain core@shell nanowires
TM
Au
Cross-sectional
view of core-shell
Ovejero et al. (letter to JMMM)

31. From NW arrays to individual core@shell NWs
SEM images of Au nanotube arrays (a),
and after filling with Fe (b), CoFe (c) and Ni (d).
Fe@Au individual nanowires after released from
the template (e).
Au Fe@Au
CoFe@Au Ni@Au

32. D. Magnin et al., Biomacromolecules 2008
Magneto-Biological functionalization: Nanowires vs. Nanoparticles ?
Non-chemotoxic induction of cancer cell
death using magnetic NWs
Contreras et al,
Int. J. Nanomedicine 2015
Osteosarcoma Cell Control with
Ni/Au segmented nanowires
B.Stadler et al.
Nanotechnology (2015)
CoPt/Au Multisegment Nanowires
Functionalization for DNA detection
Ramulu et al. J. Electrochem. Sci. (2012)

33. MAGNETIC NANO & MICRO WIRES
2.- Magnetic Mcrowires:
FMR in biphase microwires
Controlled motion of single Domain-Wall in single phase microwires
1.5 mm metallic diameter

34. Single and Bimagnetic Microwires: Preparation & Magnetics
An outer magnetic layer is grown by combined electroplating & sputtering
• Magnetic character is controlled by the choice of:
Alloys composition (soft/hard, hard/soft)
Internal/External phases thickness
Magnetostatic Bias + Magnetoelastic Interaction
Nucleus (amorphous)
Shell (polycrystalline)
BI-MAGNETIC
MICROWIRE
-40 -20 0 20 40
-1,2
-0,6
0,0
0,6
1,2
1 mm CoNi
M(x10
-3
emu) H (kA/m)
Single CoFeSiB (Soft) CoFeSiB/NiFe (Soft/Soft) FeSiB/CoNi (Soft/Hard)

35. Network Analyser-FMR in microwires
The sample holder based on commercial SMA
connectors provides reliable data up to 12 GHz
Simpler and more versatile technique than those
based in µwires as part of the TL
DUT
Irf
8 mm
Hdc
µwire Calibration: 50 Ω SMD resistor
(electrical delay= 77 ps)
Collaboration V. Raposo
(Un Salamanca)
Power Supply
Network
Analyzer
SMA Cable
Helmholtz &
Solenoid
Sample Holder
Computer control

36. Metallic diameter Dmet= 17 mm
Total diameter D = (a) 42 mm, (b) 34 mm, (c) 20 mm
FMR CoFe-base single microwires: single absorption
Various Pyrex
thickness
CoFeSiB non-magnetostrictive microwire, l ≈ -1x10-7

37. FMR CoFe-base biphase microwires: three absorption peaks
CoFeSiB soft non-magnetostrictive core, l ≈ -1x10-7
NiFe ultrasoft polycrystalline shell
Metallic diameter Dmet= 17 mm
Met. + Pyr. diameter D = (a) 42 mm, (b) 34 mm, (c) 20 mm
NiFe thickness t= 2 mm
Various Pyrex thickness

38. FMR CoFe-base biphase microwires: two absorption peaks
Various Pyrex
thickness
CoFeSiB non-magnetostrictive microwire, l ≈ -1x10-7
CoNi semi-hard polycrystalline shell Metallic diameter Dmet= 17 mm
Met. + Pyr. diameter D = (a) 42 mm, (b) 34 mm, (c) 20 mm
CoNi thickness t= 2 mm

39. CoNi shell was non
magnetically saturated, is this
the origin of the low f
absorption?
Multiple absorption FMR in bimagnetic wires: summarizing
0 1 2 3 4 5 6 7 8 9 10
40
80
120
160
200
240
280
R()
f (GHz)
4.9 kA/m
19.9 kA/m
35.1 kA/m
CoFe-FeNi (2-3 mm FeNi)
0,0 0,1 0,2 0,3 0,4 0,5 0,6
0
10
20
30
40
50f
2
(GHz
2
)
H (kOe)
FMR 1
FMR 2 (CoFe nucleus)
FMR 3 (FeNi shell)
CoFe glass-coated
linear fit
linear fit
4πMS= 11.5 kOe
4πMS= 6.9 kOe
??
• Soft/soft biphase system: CoFe/FeNi
• Soft/hard biphase system: CoFe/CoNi
FeNi shell was saturated, then a
third absorption is observed
0 1 2 3 4 5
-100
-50
0
50
100
150
200
R,X()
f (GHz)
16 kA/m
R
X
??

40. Scheme of nucleation & depinning & propagation of a single Domain Wall
(Magnetostrictive Fe rich microwires)
++ --
-
+
+
+ +
++
+
-
-
--
- -
++
+
-
- -
-
-
-
-
-
+
-
-
+
-
-
+
+
+
-
--
+
+
+
-400 -200 0 200 400
-0,8
-0,4
0,0
0,4
0,8
M(emu)x10
 H (A/m)
Hsw ~ (1/m0MsVcr) { aEg+ bEsf}
DW
Reversal spontaneously begins at one end of the wire at a critical switching field
1.5 mm metallic diameter

41. -Fluxmetric induction magnetometer (Home-designed),
based on Butta, Infante et al. Rev Sci Instrm 2009
For high sensitivity hysteresis loops and single DW dynamics
Magnetic Measurements
Voltage peaks induced at pick up coils as DW passes
t
Domain Wall velocity
Sixtus-Tonks like experiment
A single domain wall depins
from one end
propagating along the entire wire
tdv  /
1.55 1.60 1.65 1.70
-0.10
-0.05
0.00
0.05
0.10
dM/dt(a.u.)
t (ms)

42. v = S(H − H0)
be - eddy currents
br - spin relaxation
bs - structure relaxation
b reflects the
interaction DW with
defects
Single Domain Wall & Dynamics
Profiting of having a Single domain wall
for fundamental dynamics studies
Damping mechanisms
DW motion equation

43. Exp. 1.-Trapping a Domain Wall: Sixtus & Tonks–like
- Homogeneous drive field, Hdr (solenoid)
- Local field, HL
- Two symmetric pick-up coils
- Asymmetric positioning of the microwire:
essential for the depinning of the standard wall, DWst,
at the left wire’s end and its rigthward propagation
Under applied drive field by the solenoid,
a reverse domain nucleates at the left wire’s end, and
a “standard” wall depins and propagates along the wire
FeSiB microwire,
10 mm metallic diameter

44. Scheme of domain structure after a standard Domain Wall, DWst, moves
under drive field, Hdr, plus “small-amplitude” antiparallel local field
Antiparallel local-field configuration:
the Local field opposes the motion of DW by the Drive field
Braking and Trapping a Domain Wall

45. Braking &Trapping a domain wall: Antiparallel local-field configuration
DWst trapped at 4.27 mm
to the left of the local coil
Experimental (blue) & calculated (red)
Pick up 1 Pick up 2
0,000 0,001 0,002 0,003 0,004
-200
-100
0
100
200
320 360 400 440 480
0
2
4
6
H(A/m)
t (m s)
B
t (m s)
e.m.f(a.u.)
Drive field
Local field
HL>HLtrap
Drive, Hdr (blue) and Local, HL (green) fields and emf responses recorded in rigth (black) and left (red) sensing coils
HL < HLtrap
Velocity, v, of the standard wall, DWst,
under drive field Hdr= 170 A/m, as a
function of the antiparallel local field, HL.
The wall gets trapped at HL=610 A/m
Vázquez et al.
Phys. Rev. Letters 108,037201 (2012)

46. Exp. 2.-Playing with the propagation of Single DW
The sequence of colored peaks confirms
a Rightwards motion of the Single DW
for rightwards (bottom) and
leftwards (upper)
applied field
Fe79Si10B8C3 microwire
(dmet=20.5 mm, Dtot=30.5 mm)
- Multiple-coil system (2000 turns, 2 mm wide)
- Extended length: 40 cm long wires
- Square shaped 40 Hz field
A. Jimenez et al., Eur Phys J B 86, 113 (2013)
invited JEMS 2012
microwire
S1
yellow
S2
blue
S3
pink
S4
greenPick-up coils Si
“Small” Applied Field, H = ± 213 A/m
H
H

47. “Medium” Applied Field = ± 262 A/m
H
S4S3S2S1
DWst1
v
S4S3S2S1
0H 
S4S3S2S1
DWst2
v
H
v
DWrev
Single DW rightwards motion (bottom)
Two DWs moving in opposite directions (upper)
microwire
S1
yellow
S2
blue
S3
pink
S4
green
For Happ=-262 A/m, the signal at S4 (green) is
received before the one in S3 (pink) denoting
the presence of a second reverse wall, DWrev,
propagating in the opposite direction
H
H
The appearance of a second DW moving opposite

48. “Large” Applied Field = ± 281 A/m
H
S4S3S2S1
DWst1
v
S4S3S2S1
0H 
S4S3S2S1
DWst2
v
H
v
DWrev
DWst2 and DWrev arrive to S3 simultaneously:
microwire
S1
yellow
S2
blue
S3
pink
S4
green
For Happ=-281 A/m, signals at S2 (blue) and S4
(green) are picked up simultaneously.
Also, signal in S3 (pink) has higher amplitude
and reduced width.
Observing the collapse of 2 single DWs moving in opposite directions

49. www.icmm.csic.es/gnmp/
Inst. Materials Science of Madrid
David Trabada
Rafael P. del Real
Jose Miguel García
Cristina Bran
Laura Vivas
Rhimou ElKammouni
Ester Palmero
Oksana Chubykalo Yurii Ivanov
Agustina Asenjo
Group of Nanomagnetism
and Magnetization Processes
the scientific team in winter excursion by the
mountains in Segovia looking for the roasted lambPatones de Arriba,
Dec. 2015