From Event: SPIE Nanoscience + Engineering, 2018
Topological insulators (TIs) have attracted much attention due to the gapless metallic surface states (SSs) that are protected by the time-reversal symmetry (TRS). The SSs are promising particularly because of the giant spin-charge current conversion efficiencies. However, because the SSs of TIs are protected by the TRS, they are easily broken when a ferromagnetic material is deposited on the surface of TIs due to a magnetic perturbation. Meanwhile, the SSs in topological crystalline insulators (TCIs) are protected by the mirror reflection symmetry of the crystal. Thus, the influence of the breaking of the TRS by the magnetic perturbation is different in TCIs from that in other TIs. SnTe is a typical and promising TCI. The strong spin-orbit coupling in bulk SnTe is also attractive for spintronic applications. However, there have been no reports of successful spin injection into either the SSs or the bulk state of SnTe. In this study, using a high-quality epitaxial (001)-oriented Fe/ SnTe/ CdTe/ ZnTe heterostructure grown on GaAs, we have successfully observed the inverse spin Hall effect in SnTe induced by spin pumping. A relatively large spin Hall angle of ~0.01 was obtained for bulk SnTe at room temperature. This large value may be partially caused by the surface states. Our result suggests that SnTe can be used for efficient spin-charge current conversion. [S. Ohya et al., Phys. Rev. B 96, 094424 (2017).] This work was supported by Grants-in-Aid for Scientific Research and Spintronics Research Network of Japan (Spin-RNJ).
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Shinobu Ohya, Akiyori Yamamoto, Tomonari Yamaguchi, Ryo Ishikawa, Ryota Akiyama, Le Duc Anh, Shobhit Goel, Yuki K. Wakabayashi, Shinji Kuroda, and Masaaki Tanaka, "Observation of the inverse spin Hall effect in the topological crystalline insulator SnTe using spin pumping (Conference Presentation)," Proc. SPIE 10732, Spintronics XI, 1073239 (Presented at SPIE Nanoscience + Engineering: August 23, 2018; Published: 18 September 2018); https://doi.org/10.1117/12.2320140.5836441580001.