Spin Transport in the Proximity of a Ferromagnet
Chia-Ling Chien
Department of Physics and Astronomy
The Johns Hopkins University, Baltimore MD 21218
Abstract
Transport of charge, spin, and heat in a non-magnetic metal
(e.g., Pt) in the proximity of ferromagnetic metal or insulator, such
as that realized in spin transport, spin pumping, and spin Seebeck
effect (SSE) [1], have attracted much attention recently but not
without complications. For example, in the transverse SSE
geometry with an in-plane (DxT) temperature gradient, there exists also an out-of-plane (DzT)
temperature gradient in the case of thin magnetic films on substrate
that gives rise to the anomalous Nernst effect (ANE). The
voltages of SSE with DxT and ANE with DzT
are additive with the same field dependence, symmetry, and hence
inseparable [2]. In the longitudinal SSE geometry, using
exclusively DzT in a ferromagnetic
insulator (e.g., YIG), one encounters magnetic proximity effects (MPE)
[3] and new magnetoresistance (MR) in Pt that complicate SSE and other
pure spin current phenomena. Recently, we report the observation of
the intrinsic longitudinal SSE in Au/YIG without appreciable MPE
[4], whereas the new MR in Pt/YIG is likely to be associated with the
MPE.
[1] K. Uchida, S. Takahashi, K. Harii, J. Ieda, W. Koshibae, K. Ando, S. Maekawa, and E. Saitoh, Nature 455, 778 (2008).
[2] S. Y. Huang, W. G. Wang, S. F. Lee, R. Kwo, and C. L. Chien, Phys. Rev. Lett,. 107, 216604 (2011).
[3] S. Y. Huang, X. Fan, D. Qu, Y. P. Chen, W. G. Wang, J. Wu, T. Y.
Chen, J. Q. Xiao, and C. L. Chien, Phys. Rev. Lett,. 109, 107204 (2012).
[4] D. Qu, S. Y. Huang, J. Hu, R. Wu, and C. L. Chien, Phys. Rev. Lett,. 110, 067206 (2013).
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