Landau levels and Shubnikov–de Haas oscillations in monolayer transition metal dichalcogenide semiconductors

Abstract

We study the Landau level (LL) spectrum using a multi-band ${\bf{k}}\cdot {\bf{p}}$ theory in monolayer transition metal dichalcogenide semiconductors. We find that in a wide magnetic field range the LL can be characterized by a harmonic oscillator spectrum and a linear-in-magnetic field term which describes the valley degeneracy breaking. The effect of the non-parabolicity of the band-dispersion on the LL spectrum is also discussed. Motivated by recent magnetotransport experiments, we use the self-consistent Born approximation and the Kubo formalism to calculate the Shubnikov–de Haas oscillations of the longitudinal conductivity. We investigate how the doping level, the spin-splitting of the bands and the broken valley degeneracy of the LLs affect the magnetoconductance oscillations. We consider monolayer MoS _2 and WSe _2 as concrete examples and compare the results of numerical calculations and an analytical formula which is valid in the semiclassical regime. Finally, we briefly analyze the recent experimental results (Cui et al 2015 Nat. Nanotechnol. http://dx.doi.org/10.1123/ijspp.2014-0203 10 http://dx.doi.org/10.1123/ijspp.2014-0203 ) using the theoretical approach we have developed.

Keywords

• transition metal dichalcogenides
• Landau levels
• Shubnikov–de Haas oscillations
• 2-dimensional systems