Regensburg 2007 – scientific programme
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MA: Fachverband Magnetismus
MA 18: Spindependent Transport II
MA 18.6: Talk
Wednesday, March 28, 2007, 16:30–16:45, H22
current-induced dynamics in spin-valves due to non-standard angular torque dependence — •Martin Gmitra1 and Jozef Barnas2 — 1University of Regensburg, Regensburg, Germany — 2Adam Mickiewicz University, Poznan, Poland
The spin transfer phenomena in spin-valves are the subject of extensive experimental and theoretical works due to novel design and promising application of new spintronic devices. A standard spin-valve structure contains fixed and sensing magnetic layer separated by nonmagnetic or insulating layer. The current induced motion of the sensing magnetic layer is related to the angular dependence of the spin torque that gives rise to current driven switching between low and high resistive states of the valve above a certain critical value. Additionally, by application of external magnetic field the microwave steady oscillations of magnetoresistance can be induced.
In the talk, the theoretical study of asymmeric spin valve based on the macroscopic model in diffusive transport regime will be presented. Within the approach, the non-standard angular torque dependence is obtained which leads to destabilization of both the low and high resistive states. Moreover, the steady state oscillations are predicted in zero magnetic field within macrospin model. The results open an interesting way for spin transfer oscillators that do not need an applied field.