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arXiv · 2312.07944

Antiparallel spin polarization and spin current induced by thermal current and locally-broken inversion symmetry in a double-quantum-well structure

Yuta Suzuki·Yuma Kitagawa·Shin-ichiro Tezuka·Hiroshi Akera
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Abstract

Generating a nonequilibrium spin polarization with a driving force has been first realized by the electric current in a system with broken inversion symmetry and extended to that induced by the thermal current and that appearing in an inversion-symmetric system with locally-broken inversion symmetry. This paper theoretically explores the spin polarization generated by the thermal current and the locally-broken inversion symmetry in a symmetric double-quantum-well structure (DQWS). This thermally-induced spin polarization (TISP) appears in the antiparallel configuration with the TISP of two wells in opposite directions. The calculation using the Boltzmann equation in the relaxation-time approximation under the condition of zero charge current shows that the local TISP exhibits the maximum at a finite Rashba spin-orbit interaction when the electron density is fixed. This is because the local TISP in the DQWS is enhanced at the chemical potential near the bottom of the first-excited subband. This enhancement also occurs in a single quantum well with globally-broken inversion symmetry. Another finding is that the maximum of the local TISP appears at a nonzero interwell coupling. The spin current by the diffusion of the local TISP into an adjacent electrode is also calculated.

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Yuta Suzuki, Yuma Kitagawa, Shin-ichiro Tezuka, Hiroshi Akera. 2023-12-13. Antiparallel spin polarization and spin current induced by thermal current and locally-broken inversion symmetry in a double-quantum-well structure. https://arxiv.org/abs/2312.07944

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