Heat- and laser-driven non-equilibrium transport in quantum magnets
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 . 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 . 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. D. Hirobe, MS, et al, Nat. Phys. 13, 30 (2017).
 D. Hirobe, MS, et al, PRB95, 241112(R) (2017). Editor’s Suggestion.
 D. Hirobe, MS, et al, PRL123, 117202 (2019).
 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).
 H. Ishizuka and MS, PRL122, 197702 (2019); arXiv:1907.02734.
 T. N. Ikeda and MS, arXiv:1910.00146.