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arXiv · 2008.02446

Paramagnetic spin Hall magnetoresistance

Koichi Oyanagi·Juan M. Gomez-Perez·Xian-Peng Zhang·Takashi Kikkawa·Yao Chen·Edurne Sagasta·Andrey Chuvilin·Luis E. Hueso·Vitaly N. Golovach·F. Sebastian Bergeret·Fèlix Casanova·Eiji Saitoh
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Abstract

Spin Hall magnetoresistance (SMR) refers to a resistance change in a metallic film reflecting the magnetization direction of a magnet attached to the film. The mechanism of this phenomenon is spin exchange between conduction-electron spins and magnetization at the interface. SMR has been used to read out information written in a small magnet and to detect magnetization dynamics, but it has been limited to magnets; magnetic ordered phases or instability of magnetic phase transition has been believed to be indispensable. Here, we report the observation of SMR in a paramagnetic insulator Gd$_{3}$Ga$_{5}$O$_{12}$ (GGG) without spontaneous magnetization combined with a Pt film. The paramagnetic SMR can be attributed to spin-transfer torque acting on localized spins in GGG. We determine the efficiencies of spin torque and spin-flip scattering at the Pt/GGG interface, and demonstrate these quantities can be tuned with external magnetic fields. The results clarify the mechanism of spin-transport at a metal/paramagnetic insulator interface, which gives new insight into the spintronic manipulation of spin states in paramagnetic systems.

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Koichi Oyanagi, Juan M. Gomez-Perez, Xian-Peng Zhang, Takashi Kikkawa, Yao Chen, Edurne Sagasta, Andrey Chuvilin, Luis E. Hueso, Vitaly N. Golovach, F. Sebastian Bergeret, Fèlix Casanova, Eiji Saitoh. 2021-10-08. Paramagnetic spin Hall magnetoresistance. https://doi.org/10.1103/physrevb.104.134428

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