Electronic and optical properties of monolayer and few-layer InSe

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• Sam Magorrian (Manchester)
• Thursday 28 February 2019, 13:45-15:00
• Theory Library.

If you have a question about this talk, please contact Mike Gunn.

A tight-binding model is used to explore the behaviour of the few-layer bands of InSe, showing a strong electronic coupling between the layers, in contrast to the weak (van der Waals – type) binding between the crystal layers.

Oscillator strengths generated by the model are used to describe the dominant polarisation character and strength of interband optical transitions, with the principal interband transition coupling primarily to out-of-plane polarised light.

We use a band-basis continuum model to describe misaligned films of InSe which exhibit increased band gaps due to reduced electronic coupling between the layers. The continuum model is also applied self-consistently to the question of intersubband optical transitions involving electrons in gate-doped films.

Since the band edges in InSe appear in the vicinity of the Γ-point, spin-splitting at the band edges is negligible. However, interband mixing induced by spin-orbit coupling does have consequences for the polarisation of optical transitions. We analyse this effect, which is strongest in the monolayer, both using the continuum model, and by adding atomic spin-orbit coupling to the atomistic tight-binding approach. The spin-orbit splitting in the conduction band of few-layer Indium Selenide is found to be of the Rashba type, and we show how the strength of the Rashba splitting will depend on the interplay between the symmetry-breaking of the crystal structure itself, and that provided by the electric field of gates used to dope the system. We compare the predictions of the model with magnetotransport experiments showing evidence of weak antilocalisation.

This talk is part of the Theoretical Physics Seminars series.

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