Laboratorio de Fsica de Sistemas Pequeos y Nanotecnologa

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Laboratorio de Física de Sistemas Pequeños y
Nanotecnología
Ballistic Magnetoresistance in Contacts Grown in
Wires and Films Electronic Effects. N.
García LFSP-CSIC,Serrano 144, 28006 Madrid.
España, Collaborators Hai Wang, Cheng Hao, A.
Papageorgopoulos, Nikolic and E. Paz.
External Collaborators R. Ibarra, Zaragoza, M.
L. Sartorelli and A. A. Pasa,
Floriannópolis, M. Muñoz, Paris.
PRAGA (CDME, JULY 2004)
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Laboratorio de Física de Sistemas Pequeños y
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• Introduction
• 2. Atomic contact , realization, BMR and
  universality
• 3. Electrodeposited contact
• a) in wires,
• Permalloy, Ni and Cu wires with Ni,
  Co, Fe contacts
• b) in Films
• Cu films with Fe, Co, Ni and NiFe
  contacts
• 4. Magnetoresistance
• 5. Recent New Samples Multiple Contacts
  Reproducible and Stable Distributed to Different
  Labs
• 6. Perspectives

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Laboratorio de Física de Sistemas Pequeños y
Nanotecnología
Julliere Model of MR
M
M
Current
P1
P2
TMR or BMR device
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Laboratorio de Física de Sistemas Pequeños y
Nanotecnología
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Laboratorio de Física de Sistemas Pequeños y
Nanotecnología
García, Muñoz and Zhao, PRL,1999
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Laboratorio de Física de Sistemas Pequeños y
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Theory Cabrera and Falicov 1974 scattering by
domain walls, adapted by Tatara, García et al
1999 for point contacts.
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Laboratorio de Física de Sistemas Pequeños y
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PRL 89, 287203 (2002). Theory Tatara and Garcia
et al (PRL 99) using the scattering by domain
walls of Cabrera and Falicov (Fisica Statrus
Solidi 1974)
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Laboratorio de Física de Sistemas Pequeños y
Nanotecnología
Nanocontact a) overall configuration b) to d)
blow-up at the contact. The hatched region
represents the domain-wall of width ?, the
contact length l and diameter d. The arrows
indicate possible magnetic configuration of the
spin reservoirs adjacent to the contact.
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Laboratorio de Física de Sistemas Pequeños y
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Our result APL 79 4550(2001)
Chopras result PRB B 66, 020403 (2002)
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Laboratorio de Física de Sistemas Pequeños y
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Laboratorio de Física de Sistemas Pequeños y
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The configuration of Cu film
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Laboratorio de Física de Sistemas Pequeños y
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a
b
NiFe deposit contact area, obtained at 4 V/Pt,
with a different Ni/Fe ratio a) 90 10 b) 85
15.
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Laboratorio de Física de Sistemas Pequeños y
Nanotecnología
The BMR curves of iron and permalloy contacts on
Cu film respectively. In the case of iron, the
left picture, up-triangle is 1-10 loops, square
is 100-110 loops, circle is 200-210 loops. In the
case of permalloy, the right one, we measured the
sample two time, each time one hundred loops, we
show here the first ten of each time square is
1-10 loops, up-triangle is 100-110 loops. The
inserts at the top right of both curves depict
SEM scans of the contacts in mention with the
scale shown on the corresponding photos.
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Laboratorio de Física de Sistemas Pequeños y
Nanotecnología
b)
a)
a) wafer samples for nanocontact experiments.
Wafers are Cu or Permalloy b) part in circle
from a).
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Laboratorio de Física de Sistemas Pequeños y
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a)
b)
a) Morphology of 3um width thin permalloy film
after etch process. b) MR curves of the film.
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Laboratorio de Física de Sistemas Pequeños y
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a)
b)
a) The morphology of the tip area and b) MR
curves of T configuration contact area.
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Laboratorio de Física de Sistemas Pequeños y
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Manipulate the Resistance of the
Electrodeposited Ni Nanocontact by Current Pulse
Upper The curve of current pulse with 20ns
width pass through the sample. Lower The
resistance decreases by pulse. The change is
about 20 percent under zero field The current
pulse produced by the Function Generator and the
signal were recorded by a high-speed
Osicilloscope
R(H) loops with the field parallel to one
electrode and perpendicular to another, the BMR
ratio about 30.
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Laboratorio de Física de Sistemas Pequeños y
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a)
b)
c)
d)
e)
f)
a)-f) show the magnetoresistance curves of the
Sample with different measuring current, the
maximum field is up to 3000Oe with the field
parallel to the sample configuration at room
temperature.
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Laboratorio de Física de Sistemas Pequeños y
Nanotecnología
h)
i)
j)
k)
h) Shows the MR ratio is increased as the
measuring current increased i) shows the curves
of the maximum resistance divided by the minimum
resistance j) The curves of the resistance at
high field and low field with different measuring
current k) shows the bias voltage applied on the
sample at high field and low field with different
measuring current.
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Laboratorio de Física de Sistemas Pequeños y
Nanotecnología
a)
b)
c)
d)
e)
a)-e) show the magnetoresistance curves of the
Sample Three with different measuring current,
the maximum measuring field is up to 3000 Oe with
the field parallel to the sample configuration at
room temperature.
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Laboratorio de Física de Sistemas Pequeños y
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f)
g)
h)
f) Shows the magnetoresistanc ratio is decreased
as the measuring current increasedg) the bias
voltage applied on the sample at high field and
low field with different measuring currenth) the
resistance at high field divided by the
resistance at low field with different measuring
current .
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Laboratorio de Física de Sistemas Pequeños y
Nanotecnología
a)
b)
c)
d)
e)
f)
a)-f) show the magnetoresistance curves of the
sample four with different measuring current,the
maximum measuring field is up to 3000 Oe with
the field parallel to the sample configuration
at room temperature.
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Laboratorio de Física de Sistemas Pequeños y
Nanotecnología
h)
i)
h) Shows the resistance curve at high field and
low field with different measuring current i)
The Magnetoresistance ratio with different
measuring Current.


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Laboratorio de Física de Sistemas Pequeños y
Nanotecnología
NEW Samples Multiple Contacts
h)
i)
h) MR of the new samples stable and reproducible
sent to different labs (LFSP, Madrid) i) The
Magnetoresistance ratio with different measuring
current. DATA TAKEN IN MADRID of the new
samples


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h)
i)

• h) MR DATA MEASURED IN ZARAGOZA (R.IBARRA)
• I-V CURVES (HIGHLY NON LINEAR AND STRONG
  DEPENDENCE
• ON T)

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33nm R Vs T H0T de 4K a 298K sweep200 mins
muestreo5s. ZARAGOZA
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T103K, H5T
MR, T103K
T103.3K Hc-0.01T
MR, T275K
T275K, H-0.001T
T275K, H5T
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Laboratorio de Física de Sistemas Pequeños y
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Magnetoresistance
Magnetoimpedance
h) DATA MEASURED OF THE SAME SAMPLES IN UFSC
FLORIANÓPOLIS. (M. L. SARTORELLI AND A.A. PASA)
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Laboratorio de Física de Sistemas Pequeños y
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h)
i)

• DATA MEASURED OF THE SAME SAMPLES IN Thales Lab,
  ORSAY
• (M. MUÑOZ),
• MANY CYCLES FOR DIFFERENT CURRENTS, H)THE SAME
  DATA
• AT LOW FIELD NOTICE THE VARIATION OF R AND mr
  WITH CURRENT

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