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Spin current can be used to control the magnetization dynamics of a nano-magnet. There are various ways to generate spin current. Electrical current or heat current passing through a ferromagnet can generate spin current due to the spin dependent conductivity or spin-dependent Seebeck effect. Electrical current passing through a non-magnetic material with high spin-orbit coupling can generate spin current via the spin-Hall effect. Heat current passing through a non-magnet can also generate spin current due the spin-orbit coupling. This effect known as the spin-Nernst effect (SNE), has been shown recently by measuring thermally driven spin-Hall magneto-resistance [1-3]. We have shown that the spin-Nernst effect can be measured directly via a multi-terminal device with ferromagnetic Ni contacts on Pt [4]. We generated heat current in the Pt and the resultant spin current was then detected by Ni contacts. The same multi-terminal device was used to measure the spin-Hall angle for comparison with spin-Nernst angle. In a further work, we have shown that the spin current generated via spin-Nernst effect can be injected into an adjacent FM layer to exert spin-transfer torque (spin-Nernst torque) [5]. We could change the effective damping of the ferromagnet via spin-Nernst torque.
[1] S. Meyer et.al., Nat. Mater. 16, 977 (2017).
[2] P. Sheng et.al., Sci. Adv. 3, e1701503 (2017).
[3] D. J. Kim, et.al., Nat. Commun. 8, 1400 (2017).
[4] A. Bose et.al., Applied Physics Letters, 112, 162401 (2018).
[5] A. Bose et.al., Phys. Rev. B 98, 184412 (2018).
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