Density-Functional Tight-Binding Simulations of Curvature-Controlled Layer Decoupling and Band-Gap Tuning in BilayerMoS2

Autor:	Ioanna Fampiou, Pekka Koskinen, Ashwin Ramasubramaniam
Rok vydání:	2014
Předmět:	Materials science Tight binding Condensed matter physics Band gap Bilayer Monolayer Valleytronics General Physics and Astronomy Periodic boundary conditions Electronic structure Symmetry (physics)
Zdroj:	Physical Review Letters. 112
ISSN:	1079-7114 0031-9007
DOI:	10.1103/physrevlett.112.186802
Popis:	Monolayer transition-metal dichalcogenides (TMDCs) display valley-selective circular dichroism due to the presence of time-reversal symmetry and the absence of inversion symmetry, making them promising candidates for valleytronics. In contrast, in bilayer TMDCs both symmetries are present and these desirable valley-selective properties are lost. Here, by using density-functional tight-binding electronic structure simulations and revised periodic boundary conditions, we show that bending of bilayer MoS2 sheets breaks band degeneracies and localizes states on separate layers due to bending-induced strain gradients across the sheets. We propose a strategy for employing bending deformations in bilayer TMDCs as a simple yet effective means of dynamically and reversibly tuning their band gaps while simultaneously tuning valley-selective physics.
Databáze:	OpenAIRE
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