Here we show spin transport and spin relaxation phenomena in germanium (Ge) up to room temperature. Using four-terminal nonlocal voltage and Hanle-effect measurements in lateral spin-valve devices with ferromagnet/Ge Schottky-tunnel contacts, we detected reliable spin transport from low temperatures to room temperature in n-Ge and discussed the spin relaxation mechanism in the conduction band of Ge [1-4]. We also demonstrated the detection of the spin transport in p-Ge by using vertically stacked structures including ferromagnet/Ge interfaces on Si [5,6]. From the magnitude of the spin signals, we also discussed the spin relaxation in p-Ge up to room temperature. From the viewpoint of low contact resistance for applications in the field of group-IV semiconductor spintronics, our technologies are more suitable than ferromagnet/MgO tunnel contacts.
[1] Y. Fujita, KH et al., Phys. Rev. B 94, 245302 (2016).
[2] M. Yamada, KH et al., Phys. Rev. B 95, 161304(R) (2017).
[3] Y. Fujita, KH et al., Phys. Rev. Appl. 8, 014007 (2017).
[4] M. Yamada, KH et al., Appl. Phys. Exp. 10, 093001 (2017).
[5] M. Kawano, KH et al., Appl. Phys. Lett. 109, 022406 ¬(2016).
[6] M. Kawano, KH et al., Phys. Rev. Mater. 1, 034604 (2017).
The author appreciates good collaborative research with Prof. K. Sawano, Prof. V. Lazarov, and the colleagues of our group in Osaka University. This work was partly supported by KAKENHI (No. 25246020, 16H02333, 17H06120, 26103003) from JSPS/MEXT.
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