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In the last decades, non-equilibrium phenomena have been intensively explored and several theoretical methods treating them have been developed. Spintronics, electronics, mesoscopic physics, non-equilibrium statistical physics, multiferroics, optics, cold atoms, etc. have abundantly contributed to the development. Motivated by these progresses, in recent years, we have tried to find/explore new interdisciplinary topics among these fields, especially, focusing on heat- [1,2,3] or laser-driven [4,5,6] phenomena.

In the present seminar, I would like to report two of our recent results for non-equilibrium spin transport. The first topic is the spin Seebeck effect in a spin-nematic state [3]. This offers a route between spintronics and quantum magnetism. The second is the theoretical study of the laser-driven rectification of DC spin current in non-centrosymmetric magnetic insulators [5]. This study is the first proposal for the spin-current version of shift current (spin version of solar cell), and results from connecting several ideas in spintronics, optics, multiferroics, and non-equilibrium physics. I would like to explain these results focusing on their essential aspects.

[1] D. Hirobe, MS, et al, Nat. Phys. 13, 30 (2017).
[2] D. Hirobe, MS, et al, PRB95, 241112(R) (2017). Editor’s Suggestion.
[3] D. Hirobe, MS, et al, PRL123, 117202 (2019).
[4] H. Fujita and MS, PRB95, 054421 (2017), Editor’s suggestion; PRB96, 060407(R) (2017); Sci. Rep. 8, 15738 (2018); H. Fujita, Y. Tada, and MS, New. J. Phys. 21, 073010 (2019).
[5] H. Ishizuka and MS, PRL122, 197702 (2019); arXiv:1907.02734.
[6] T. N. Ikeda and MS, arXiv:1910.00146.

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