2016.06.21 mano ucm nanofrontmag
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J. L. Vicent Departamento Fisica de Materiales
Facultad Ciencias Físicas Universidad Complutense
28040 Madrid (Spain) IMDEA-Nanociencia
28049 Madrid (Spain)
Grupo de Magnetismo y Nanolitografía-UCM 4. Mejora de las propiedades magnéticas y eléctricas de los
superconductores mediante la fabricación de nanoestructuras híbridas
Type II Supercondutors
Vortices
Mixed State
Tc
Mixed
State
Normal
State
Meissner
State
Hc2
Hc1
NbSe2
Hess et al. PRL62,214 (1989)
Abrikosov Lattice
Hc1<H<Hc2
Mixed State
Vortices on the move ?
vBE
Magnetic Field
VDC
R(H)
B
B
0
Current Density
J
oL JF
v
J
E
FL ,v
Vortices move J
Bc1<B<Bc2
Mixed State
Vortex motion causes energy dissipation:
Resistance ≠ 0
&
Magnetic pinning
Local depression of the
superconductivity
Core pinning
r 2
Js
ns(r)
H
0=h/2e=2.067×10-15 Wb Superconducting energy is
minimized by locating vortices in defects
PINNING MECHANISMS Vortex structure
sketch
Pinning center
Minimum of potential
Pinning Force Fp
Decrease vortex velocity
Minimum in Resistance
0 FL Fp
V(x)
R
-4 -3
-2
-1 1
2
3
4
5 -5
-0.6 -0.4 -0.2 0.0 0.2 0.4 0.610
-5
10-4
10-3
10-2
10-1
100
R(
)
H(kOe)
Superconductor Defect
Película de Nb
Array dots Si
100 nm
-0.6 -0.4 -0.2 0.0 0.2 0.4 0.610
-5
10-4
10-3
10-2
10-1
100
R(
)
H(kOe)Rectangular lattice a=400nm b=600nm
ΔH = 85.3 Oe
a
b
S
0
0
0
0
axb
nHn
0
Minima in Resistance Vortex density =n· Pinning center density
-4 -3
-2
-1 1
2
3
4
5 -5
0nS
nB Matching Fields
Vortex lattice u.c. area S
n = Vortices per u.c.
0.99Tc 100 mA
100 nm Nb + 40 nm Ni dots
Superconductor Nb Defectos: Cu, Si, Ni, Co, Py, a-NdCo5, Co/Pd (multicapas)
Magnetism enhances superconductivity Field induced superconductivity
V AV
Lange, van Bael, Bruynseraede,Moshchalkov PRL 90 (2003)
H=0
H0
SC SC
Superconductor
Superconductor
Magnets with out of plane Mz
Magnets with out of plane Mz
Dot Co/Pd
Nb
-0.4 -0.2 0.0 0.2 0.410
-3
10-2
10-1
100
10 mA
20 mA
50 mA
100 mA
R (
)H (kOe)
-2 -1 0 1 210
-4
10-3
10-2
10-1
100
Desimanado
Imanado
R/R
N
H/Hmatching
Dot Si
Nb
-0,4 -0,3 -0,2 -0,1 0,0 0,1 0,2 0,3 0,4
10-5
10-4
10-3
10-2
10-1
100
+Msat
-Msat
R(
)
H(kOe)
Pinning en N= -1 para distintas
memorias magneticas de los dots
2.5 mA
T=0.99Tc
Tc=8.385 K
Array of Ni dots (400 nm x 400 nm) /Nb film
+1 -1
Dot Ni
Nb Nb Nb
-0.15 -0.10 -0.05 0.00 0.05 0.10 0.15
0.0
1.0x10-3
2.0x10-3
3.0x10-3
Desde -3 kOe
Desde -1 kOe
Desde -0.4 kOe
Desde -0.3 kOe
Desde -0.25 kOe
Desde 2 kOe
Desde 0.8 kOe
Desde 0.5 kOe
Desde 0.35 kOe
Desde 0.25 kOe
R(
)
H(kOe)
Pinning en N= -1 para distintas
memorias magneticas de los dots
2.5 mA
T=0.99Tc
Tc=8.385 K
Dot Ni
Nb Nb Nb
-0,4 -0,3 -0,2 -0,1 0,0 0,1 0,2 0,3 0,4
10-5
10-4
10-3
10-2
10-1
100
+Msat
-Msat
R
()
H(kOe)
Pinning en N= -1 para distintas
memorias magneticas de los dots
2.5 mA
T=0.99Tc
Tc=8.385 K
Three-state memory nanodevice: +1 (M =+Mz); 0 (M = 0); -1 (M =-Mz);
Reading nanodevice: Zero output signal (VDC = 0) for specific value of Happl which depends on how the
device is built.
Happl.= 0
Happl.≠ 0
Input signals: ac currents Output signals: dc voltages
Nb/(Co/Pd)
-1,0 -0,5 0,0 0,5 1,0
-20
-10
0
10
20
Vd
c, m
ax (mV)
MR / MS
1 2 3 4 5 6-20
-10
0
10
20
Vd
c(m
V)
Iac
(mA)
MR/MS = 0.65
- Vdc, max
+Vdc, max
del Valle et al. Sci. Rep. (2015)
+1
0
-1
T = 0.99Tc
Remanent magnetic states control ratchet effects
8.40 8.42 8.44 8.46 8.48 8.50 8.52
0
100
200
300
400
500
T(K)
H(O
e)
R / RN
0.0 0.5 1.0
Hcompensation = 240 Oe
Hmatching= 36 Oe
A
C
B
C
B
A
Hcompensation and Hmatching depend on the sample design.
Happl
R / RN
0.0 0.5 1.0
8,42 8,44 8,46 8,48 8,50 8,520
100
200
300
400
500
T(K)
H(O
e)
0 100 200 300 400
-20
-10
0
10
20
Vd
c, m
ax (mV)
H (Oe)-1,0 -0,5 0,0 0,5 1,0
-20
-10
0
10
20
Vd
c, m
ax (mV)
MR / MS
+1
0
-1
Happl = 0
Closing….
A Alicia Gomez Javier del V
Javier del Valle JaviEer del V Elvira Gonzalez
The
END
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