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MA: Fachverband Magnetismus

MA 54: Spin Excitations I

MA 54.7: Talk

Thursday, March 17, 2011, 16:30–16:45, HSZ 04

Theory of ac driven resonant spin amplification and depletion in FNF spin valves: prediction of negative GMR — •Denis Kochan, Martin Gmitra, and Jaroslav Fabian — University of Regensburg

Parallel (P) and antiparallel (AP) configurations of FNF junctions have, in a dc regime, different resistivities (AP>P), giving rise to the giant magnetoresistance (GMR) effect. This can be explained within the spin diffusion model.

We extend the model to include ac phenomena and predict resonant amplification and depletion of spin accumulation in the P and AP configurations, respectively. As a result, the spin valve impedance shows oscillations as a function of the driving ac frequency, with periods of negative GMR.

From the spin-valve oscillation periods, which are experimentally accessible, the time-dependent spin diffusion model allows to extract, all electronically, the spin relaxation times without additional input.

This work is supported by the DFP SFB 689.