Magnetoelectronic Spin Transfer Torque,Dissipation,and Noise

Tuesday 8 september 2009 at 4pm

CNRS Bât E, conference room "Louis Weil" on 3rd floor

Arne Brataas (Norwegian University of Science and Technology, Trondheim)

Arne Brataas (Norwegian University of Science and Technology, Trondheim) 

An electric current sent through multilayers of normal metals (N) and ferromagnets (F) can excite the ferromagnetic order parameter and even reverse the magnetization [1]. Similarly, a precessing ferromagnet emits spin-currents to adjacent conductors [2]. Additionally, spin current noise in normal electric conductors in contact with nanoscale ferromagnets can be detected by an increase in the magnetization noise by means of a fluctuating spin-transfer torque [3]. Johnson-Nyquist noise in the spin current is related to the increased Gilbert damping due to spin pumping, in accordance with the fluctuation-dissipation theorem. We will discuss all these phenomena in a unified picture using magnetoelectronic circuit theory and the Onsager reciprocity relations [4,5].

[1] L. Berger, Phys. Rev. B. 54, 9353 (1996); J. Slonczewski, J. Magn. Magn.. Mater. 159, L1, (1996); for a review, see D. C. Ralph, M. D. Stiles, J. Magn. Magn. Mater. 20, 1190 (2008).

[2] Y. Tserkovnyak, A. Brataas, and G. E. W. Bauer, Phys. Rev. Lett. 88,117601 (2002).

[3] J. Foros, A. Brataas, Y. Tserkovnyak, and G. E. W. Bauer, Phys. Rev. Lett. 95, 016601 (2005).

[4] for a review, see Y. Tserkovnyak, A. Brataas, G. E. W. Bauer, and B.I. Halperin, Rev. Mod.Phys. 77, 1375 (2005).

[5] A. Brataas, Y. Tserkovnyak, and G. E. W. Bauer, Phys. Rev. Lett. 101, 037207 (2008); K. Hals, A. K. Nguyen, and A. Brataas, Phys. Rev. Lett. 102,256601 (2009).

Download the abstract