Abstract
It is experimentally shown that the critical current for onset of spin torque instability in current-perpendicular-to-plane spin valves can be strongly increased using “synthetic-ferrimagnet” free layers of form (). However, this increase occurs for only one polarity of bias current. A two-macrospin model is shown to reproduce the observations. The model suggests that this phenomenon is related to a polarity-dependent, spin torque-induced coresonance between the two natural dynamic modes of the couple. The coresonance condition facilitates energy transfer out of the spin-torque destabilized mode into the other stable mode whose effective damping (or line width) is strongly enhanced by spin torques.
- Received 14 July 2008
DOI:https://doi.org/10.1103/PhysRevLett.101.247205
©2008 American Physical Society
Synopsis
Putting a damper on the spin-torque effect
Published 11 December 2008
The effects of torques caused by spin-polarized currents are often unwanted in magnetic nanostructures, but they can be diminished with the right design.
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