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| Spin current, a flow of electrons' spins in a solid, is the key concept in spintronics that will allow the achievement of efficient computing devices, and energy converters. I here review phenomena which allow us to use spin currents in insulators [1]: inverse spin-Hall effect [2,3], spin pumping, and spin Seebeck effect [3,4]. We found that spin pumping and spin torque effects appear at an interface between an insulator YIG and Pt. Using this effect, we can connect a spin current carried by conduction electrons and a spin-wave spin current flowing in insulators. Seebeck effect (SSE) is the thermal spin pumping [4]. The SSE allows us to generate spin voltage, potential for driving nonequilibrium spin currents, by placing a ferromagnet in a temperature gradient. Using the inverse spin-Hall effect in Pt films, we measured the spin voltage generated from a temperature gradient in various ferromagnetic insulators.
REFERENCES
[1] Y. Kajiwara & E. Saitoh et al. Nature 464 (2010) 262.
[2] E. Saitoh et al., Appl. Phys. Lett. 88 (2006) 182509.
[3] K. Uchida & E. Saitoh et al., Nature 455 (2008)778.
[4] K. Uchida & E. Saitoh et al., Nature materials 9 (2010) 894. |
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