TY - JOUR
T1 - Absorption of diffusive spin current in surface and bulk states of a topological insulator
AU - Nomura, Akiyo
AU - Nasaka, Nariaki
AU - Tashiro, Takaharu
AU - Sasagawa, Takao
AU - Ando, Kazuya
N1 - Funding Information:
The authors thank K. Chen and S. Zhang of University of Arizona for helpful discussions. This work was supported by PRESTO-JST (Grants No. 13415036 and No. JPMJPR1323), JST-CREST (Grant No. JPMJCR16F2), JSPS KAKENHI Grants No. 26220604, No. 26103004, and No. 16H03847, JSPS Core-to-Core Program, and Spintronics Research Network of Japan (Spin-RNJ).
Publisher Copyright:
© 2017 American Physical Society.
PY - 2017/12/28
Y1 - 2017/12/28
N2 - We report the absorption of a diffusive spin current in a bulk-carrier compensated topological insulator: Sn 0.02 -Bi 1.08 Sb 0.9 Te 2 S (Sn-BSTS). By injecting spins into a Sn-BSTS crystal from a ferromagnetic metal using spin pumping, we found that the magnetic damping of the ferromagnetic layer is enhanced due to the absorption of the spin current in the surface and bulk states of the topological insulator. We found that the damping enhancement depends critically on temperature, which allows us to disentangle the spin absorption in the surface and bulk states, owing to the nearly perfect carrier compensation in the bulk part at low temperature. Our results show that the absorption of the spin current is dominated by the surface state of the Sn-BSTS crystal at low temperature, whereas the spin absorption in the surface state is comparable to that in the bulk state near room temperature. The coexistence of the spin absorption in the surface and bulk states has been demonstrated in two different systems, where the surface state is coupled with the dynamical magnetization through the diffusive spin current or exchange coupling. These results will be essential for quantitative understanding of the spin absorption and spin-charge conversion due to the spin-momentum locked surface state of topological insulators.
AB - We report the absorption of a diffusive spin current in a bulk-carrier compensated topological insulator: Sn 0.02 -Bi 1.08 Sb 0.9 Te 2 S (Sn-BSTS). By injecting spins into a Sn-BSTS crystal from a ferromagnetic metal using spin pumping, we found that the magnetic damping of the ferromagnetic layer is enhanced due to the absorption of the spin current in the surface and bulk states of the topological insulator. We found that the damping enhancement depends critically on temperature, which allows us to disentangle the spin absorption in the surface and bulk states, owing to the nearly perfect carrier compensation in the bulk part at low temperature. Our results show that the absorption of the spin current is dominated by the surface state of the Sn-BSTS crystal at low temperature, whereas the spin absorption in the surface state is comparable to that in the bulk state near room temperature. The coexistence of the spin absorption in the surface and bulk states has been demonstrated in two different systems, where the surface state is coupled with the dynamical magnetization through the diffusive spin current or exchange coupling. These results will be essential for quantitative understanding of the spin absorption and spin-charge conversion due to the spin-momentum locked surface state of topological insulators.
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U2 - 10.1103/PhysRevB.96.214440
DO - 10.1103/PhysRevB.96.214440
M3 - Article
AN - SCOPUS:85039441366
SN - 2469-9950
VL - 96
JO - Physical Review B-Condensed Matter
JF - Physical Review B-Condensed Matter
IS - 21
M1 - 214440
ER -