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arXiv · 1706.06149

Proximity effects in bilayer graphene on monolayer WSe$_2$: Field-effect spin-valley locking, spin-orbit valve, and spin transistor

Martin Gmitra·Jaroslav Fabian
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Abstract

Proximity orbital and spin-orbit effects of bilayer graphene on monolayer WSe$_2$ are investigated from first-principles. We find that the built-in electric field induces an orbital band gap of about 10 meV in bilayer graphene. Remarkably, the proximity spin-orbit splitting for holes is two orders of magnitude---the spin-orbit splitting of the valence band at K is about 2 meV---more than for electrons. Effectively, holes experience spin-valley locking due to the strong proximity of the lower graphene layer to WSe$_2$. However, applying an external transverse electric field of some 1 V/nm, countering the built-in field of the heterostructure, completely reverses this effect and allows, instead for holes, electrons to be spin-valley locked with 2 meV spin-orbit splitting. Such a behavior constitutes a highly efficient field-effect spin-orbit valve, making bilayer graphene on WSe$_2$ a potential platform for a field-effect spin transistor.

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Martin Gmitra, Jaroslav Fabian. 2017-06-19. Proximity effects in bilayer graphene on monolayer WSe$_2$: Field-effect spin-valley locking, spin-orbit valve, and spin transistor. https://doi.org/10.1103/physrevlett.119.146401

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