nanomagnet state Reinier van Mourik 12 Charles Rettner 1 Bert Koopmans 2 Stuart Parkin 1 1 IBM Almaden Research Center San Jose CA 2 Eindhoven University of Technology Eindhoven the Netherlands ID: 694135
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Slide1
Domain wall pinning dependent on nanomagnet state
Reinier van Mourik1,2, Charles Rettner1, Bert Koopmans2, Stuart Parkin1
1. IBM Almaden Research Center, San Jose, CA2. Eindhoven University of Technology, Eindhoven, the Netherlands
BB-03Slide2
Introduction
Magnetic Domain Walls for memory and logicDynamics of magnetic domain walls important for applicationsPrecise control of DW position required, for example by pinning Parkin, S. S. P., M. Hayashi, et al. (2008). "Magnetic domain-wall racetrack memory." Science 320(5873): 190-194.
Memory
Logic
Allwood
, D. A., G.
Xiong
, et al. (2005). "Magnetic Domain-Wall Logic."
Science
309(5741): 1688-1692.
Slide3
Introduction
OutlineExperimental setupDomain wall pinned at and depinned from nanomagnet siteResultsSignificant difference in depinning field for two nanomagnet statesDiscussionDomain wall fine structure responsible for differenceApplicationsTunable pinning site or nanomagnet readoutConclusions
DWSlide4
Methods
Experimental setup
AMR and Hall bar register
depinning
of DW
nanomagnet
Py
60x90x10nm
AMR read
hall bar read
1. inject
DW
2. propagate
DW by H field
3. read
resistance change in AMR and Hall bar
PMA
[
CoNi
]
n
nanowire
, 60-140nm wide
DW
Domain wall injection line
Hall bar
pulser
H
AMR
Hall bar
0
H
depSlide5
Methods
Experimental setup
Depinning
field is measured for both
nanomagnet
states
nanomagnet
Py
60x90x10nm
AMR read
hall bar read
1. inject
DW
2. propagate
DW by H field
3. read
resistance change in AMR and Hall bar
PMA [
CoNi
]
n
nanowire, 60-140nm wide
DW
Domain wall injection line
Hall bar
pulser
H
AMR
Hall bar
0
H
depSlide6
Results
Depinning field differenceMagnetic field required to propagate DW past nanomagnet differs by 10 mT for both states.
10 mT!
Depinning
field difference increases with wire width.
typical result
wire width dependenceSlide7
Discussion
Micromagnetic energy calculation
DW fine structure introduces asymmetric component in energy landscape so
is higher in right-magnetized case.
-200
-100
0
100
200
-1.5
-1
-0.5
0
0.5
1
DW position [nm]
energy [aJ]
top view
side viewSlide8
Application
Application potential
H
probe
Nanomagnet
acts as a DW gate if the DW is propagated at a “probe field”
Application as:
tunable DW pinning site
nanomagnet
readout
AMR high
AMR high
AMR lowSlide9
AMR
AMR
Application
Domain wall pinning for use in NML readout
In
Nanomagnetic
Lo
gic, information is propagated along arrays of
nanomagnets
through
magnetostatic
coupling.
Output magnet can be read out by DW pinning technique
Each
nanomagnet
can have its own nanowire.
AMR
injection line
DW
Imre
, A., G.
Csaba
, et al. (2006). "Majority logic gate for magnetic quantum-dot cellular automata."
Science
311(5758): 205-208
.Slide10
Conclusion
ConclusionIn-plane nanomagnet above PMA nanowire is single-magnet domain wall pinning site where the pinning strength depends on the nanomagnet state.The depinning field can differ by 10 mT and depends on wire width. The DW fine structure is responsible for the depinning field asymmetry. DW pinning can be applied in logic and memory applications.
slides & contact: http://tinyurl.com/RvM-IBM