Mr. Ken-ichi Uchida (Institute for Materials Research, Tohoku University)
"Spin-Seebeck Effect"
Recent studies on spintronics [1] and spin caloritronics [2] have revealed that a spin current, a flow of spin angular momentum, is strongly coupled with a heat current in various magnetic systems. From both basic science and applied engineering points of view, the interplay of these two currents is of crucial importance.
The spin-Seebeck effect (SSE) [3-6] is a phenomenon enabling the conversion of heat currents into spin voltage, a potential for driving nonequilibrium spin currents, in ferromagnets. The observation of the SSE has been realized by the spin-detection technique based on the inverse spin-Hall effect [7].
In this talk, I will report
(1) experimental observations and mechanisms of the SSE in ferromagnetic metals [3] and insulators [4],
(2) a phonon-mediated SSE as the origin of long-range spin-voltage profile [6], and
(3) an acoustic spin pumping: a direct generation of spin currents from sound waves [6].
Remaining open questions will also be discussed.
[1] S. Maekawa (ed.) Concepts in Spin Electronics (Oxford University Press, Oxford, 2006).
[2] G. E. W. Bauer, A. H. MacDonald, and S. Maekawa (eds), Spin Caloritronics, Special Issue of Sol. Stat. Commun. (Elsevier, Amsterdam, 2010).
[3] K. Uchida, S. Takahashi, K. Harii, J. Ieda, W. Koshibae, K. Ando, S. Maekawa, and E. Saitoh, Nature 455, 778 (2008).
[4] K. Uchida, J. Xiao, H. Adachi, J. Ohe, S. Takahashi, J. Ieda, T. Ota, Y. Kajiwara, H. Umezawa, H. Kawai, G. E. W. Bauer, S. Maekawa, and E. Saitoh, Nature Mater. 9, 894 (2010).
[5] C. M. Jaworski, J. Yang, S. Mack, D. D. Awschalom, J. P. Heremans, and R. C. Myers, Nature Mater. 9, 898 (2010).
[6] K. Uchida, H. Adachi, T. An, T. Ota, M. Toda, B. Hillebrands, S. Maekawa, and E. Saitoh, Nature Mater. (in press).
[7] E. Saitoh, M. Ueda, H. Miyajima and G. Tatara, Appl. Phys. Lett. 88, 182509 (2006).