domain wall pinning dependent on nanomagnet state
DESCRIPTION
Reinier van Mourik 1,2 , 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. Domain wall pinning dependent on nanomagnet state. BB-03. - PowerPoint PPT PresentationTRANSCRIPT
© 2009 IBM CorporationMMM 2013 | 2013-11-05 | IBM/TUe © 2013 IBM Corporation
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-03
IBM Research
MMM 2013 | 2013-11-05 | IBM/TUe © 2013 IBM Corporation
Introduction
Magnetic Domain Walls for memory and logic Dynamics of magnetic domain walls important for
applications
Precise 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.
IBM Research
MMM 2013 | 2013-11-05 | IBM/TUe © 2013 IBM Corporation
Introduction
Outline
Experimental setup– Domain wall pinned at and depinned from nanomagnet site
Results– Significant difference in depinning field for two nanomagnet states
Discussion– Domain wall fine structure responsible for difference
Applications– Tunable pinning site or nanomagnet readout
Conclusions
DW
IBM Research
MMM 2013 | 2013-11-05 | IBM/TUe © 2013 IBM Corporation
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
Dom
ain wall injection line
Hall bar
pulser
H
AMRHall bar
0 Hdep
IBM Research
MMM 2013 | 2013-11-05 | IBM/TUe © 2013 IBM Corporation
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
Dom
ain wall injection line
Hall bar
pulser
H
AMRHall bar
0 Hdep
IBM Research
MMM 2013 | 2013-11-05 | IBM/TUe © 2013 IBM Corporation
Results
Depinning field difference
Magnetic 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 dependence
IBM Research
MMM 2013 | 2013-11-05 | IBM/TUe © 2013 IBM Corporation
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]
ener
gy [a
J]
top view side view
IBM Research
MMM 2013 | 2013-11-05 | IBM/TUe © 2013 IBM Corporation
Application
Application potential
Hprobe
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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 highAMR low
IBM Research
MMM 2013 | 2013-11-05 | IBM/TUe © 2013 IBM Corporation
AMR AMR
Application
Domain wall pinning for use in NML readout
In Nanomagnetic Logic, 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.
IBM Research
MMM 2013 | 2013-11-05 | IBM/TUe © 2013 IBM Corporation
Conclusion
Conclusion
In-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.
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