Argonne National Laboratory

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Current-induced Spin Wave Dynamics: Detection of Non-adiabatic Spin Transfer Torque in Adiabatic Limit

Materials Science Seminar
Koji Sekiguchi, Keio University
November 2, 2012 11:00AM to 12:00PM
Building 223, Room S105
Spin-polarized current flowing though ferromagnet can exert torques on various local magnetic structures: spin waves, magnetic vortex core, and domain walls. Among these, the interplay between spin waves and spin polarized electron transport figures out the basic nature of spin transfer physics [1].

In this talk, I would like to report on the current-induced Doppler shift which sheds a new light on the interplay between spin polarized transport and magnetization dynamics [2]. By working in time-domain, the contribution of the non-adiabatic torque to spin dynamics is extracted as a change of spin-wave waveform. Since the spin waves used in this experiment have long wave-lengths, the spin of electron adiabatically obeys to the local magnetic structure. The detection of non-adiabatic contribution in the adiabatic limit suggests a microscopic clue to understand the spin transport in ferromagnetic structures. By improving the resolution of propagating spin wave spectroscopy to determine SW amplitude, it could serve as a standard tool to estimate the above three parameters governing the STT physics.

[1] V. Vlaminck and M. Bailleul, Science 322, 410 (2008).
[2] K. Sekiguchi et. al., Phys. Rev. Lett. 108, 017201(2012).