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PRODID:UW-Madison-Physics-Events
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UID:UW-Physics-Event-1592
DTSTART:20091105T160000Z
DURATION:PT1H0M0S
DTSTAMP:20260422T145318Z
LAST-MODIFIED:20090828T162159Z
LOCATION:5310 Chamberlin
SUMMARY:Invariant form of spin-transfer switching condition\, R. G. He
 rb Condensed Matter Seminar\, Yaroslaw Bazaliy\, University of South C
 arolina
DESCRIPTION:Spin-transfer torque is a result of a non-equilibrium magn
 etic interaction induced by a flow of electric current. In nano-size d
 evices spin transfer is a mechanism for current-induced magnetic switc
 hing\, an effect with many applications in computer memory and logic. 
 Calculations of critical switching currents were performed analyticall
 y and numerically for many systems. However\, a clear physical interpr
 etation of the results was available only in special cases. We firstly
  derive an invariant form of the current-induced switching condition a
 nd show that there exists a figure of merit for the current ability to
  destabilize a minimum of magnetic energy and induce switching. The re
 sulting approach based on the "switching ability" of the current provi
 des an intuitive physical picture of the switching behavior in devices
  of any geometry. We secondly consider the problem of current-induced 
 stabilization of the saddle points and show that it happens via a diff
 erent mechanism due to the topological restrictions. Saddle points are
  normally stabilized by a current-induced merger with other equilibria
 . Finally\, we present and emerging full picture of possible switching
  scenarios in spin torque devices.
URL:https://www.physics.wisc.edu/events/?id=1592
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