open access

https://hdl.handle.net/2115/90718

Spin current between buckled atomic layers with a twist generated by locally broken inversion symmetry

英語

2023-09-25

American Physical Society (APS)

Physical Review B

108(11)

115431

Current-induced spin polarization (CISP), which appears when the inversion symmetry is broken, has been experimentally shown to generate spin currents. We have demonstrated in our recent theory that the antiparallel CISP in a double-quantum-well structure with the inversion symmetry can also create spin currents. In this paper we consider the sublattice-staggered CISP in a group-IV buckled atomic layer and theoretically study the spin current extracted from the spin-polarized atomic layer into another with identical structure. We derive a formula for the interlayer spin current in both the presence and the absence of the inversion symmetry and show that the interlayer spin current, in the inversion-symmetric case, additionally has a contribution from intersubband spin matrix elements due to spin degeneracy which is comparable in magnitude to that from intrasubband matrix elements. We calculate the interlayer spin current as a function of the interlayer twist angle using the tightbinding model and the Boltzmann equation in the relaxation-time approximation and choosing silicene as an example atomic layer. We show that the interlayer spin current created by the sublattice-staggered CISP in inversion-symmetric silicene is comparable in magnitude to that obtained from silicene with a 1 V/nm out-ofplane electric field applied to break the inversion symmetry. We find that the calculated interlayer spin current exhibits various features by twisting two layers. Most interesting is that the twist, which breaks the mirror symmetry to make the system chiral, gives rise to the component of the interlayer spin current with in-plane spin direction perpendicular to the CISP in addition to that parallel to the CISP.

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©[2023] American Physical Society

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