Density-Dependent Quantum Hall States and Zeeman Splitting in Monolayer and Bilayer WSe${}_2$

Abstract

We report a study of the quantum Hall states (QHSs) sequence of holes in mono- and bilayer WSe${}_2$. The QHSs sequence transitions between predominantly even and predominantly odd filling factors as the hole density is tuned in the range $1.6-12\times 10^{12}$ cm${}^{-2}$. The QHSs sequence is insensitive to the transverse electric field, and tilted magnetic field measurements reveal an insensitivity of the QHSs sequence to the in-plane magnetic field, evincing that the hole spin is locked perpendicular to the WSe${}_2$ plane. These observations imply that the QHSs sequence is controlled by the Zeeman-to-cyclotron energy ratio, which remains constant as a function of perpendicular magnetic field at a fixed carrier density, but changes as a function of density due to strong electron-electron interaction.

5 pages, 4 figures