Spin-orbit coupling in elemental two-dimensional materials

Kurpas, Marcin and Faria, Paulo E. and Gmitra, Martin and Fabian, Jaroslav (2019) Spin-orbit coupling in elemental two-dimensional materials. PHYSICAL REVIEW B, 100 (12): 125422. ISSN 2469-9950, 2469-9969

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Abstract

The fundamental spin-orbit coupling and spin mixing in graphene and rippled honeycomb lattice materials silicene, germanene, stanene, blue phosphorene, arsenene, antimonene, and bismuthene is investigated from first principles. The intrinsic spin-orbit coupling in graphene is revisited using multiband k . p theory, showing the presence of nonzero spin mixing in graphene despite the mirror symmetry. However, the spin mixing itself does not lead to the the Elliott-Yafet spin relaxation mechanism, unless the mirror symmetry is broken by external factors. For other aforementioned elemental materials we present the spin-orbit splittings at relevant symmetry points, as well as the spin admixture b(2) as a function of energy close to the band extrema or Fermi levels. We find that spin-orbit coupling scales as the square of the atomic number Z, as expected for valence electrons in atoms. For isolated bands, it is found that b(2) follows a scaling law close to b(2) similar to Z(4). The spin-mixing parameter also exhibits giant anisotropy which, to a large extent, can be controlled by tuning the Fermi level. Our results for b(2) can be directly transferred to spin relaxation time due to the Elliott-Yafet mechanism, and therefore provide an estimate of the upper limit for spin lifetimes in materials with space inversion center.

Item Type: Article
Uncontrolled Keywords: CONDUCTION ELECTRONS; EPITAXIAL-GROWTH; RELAXATION; PHOSPHORUS; SILICENE; METALS; LAYER;
Subjects: 500 Science > 530 Physics
Divisions: Physics > Institute of Theroretical Physics
Physics > Institute of Theroretical Physics > Chair Professor Richter > Group Jaroslav Fabian
Depositing User: Dr. Gernot Deinzer
Date Deposited: 30 Mar 2020 05:15
Last Modified: 30 Mar 2020 05:15
URI: https://pred.uni-regensburg.de/id/eprint/26243

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