Large effective mass and interaction-enhanced Zeeman splitting of $K$-valley electrons in MoSe$_2$

TL;DR

This study investigates the magnetotransport properties of high-mobility electrons in monolayer and bilayer MoSe$_2$, revealing an effective mass of 0.8 times the electron mass and interaction-enhanced Zeeman splitting affecting quantum Hall states.

Contribution

It provides the first detailed analysis of effective mass and Zeeman energy enhancement in MoSe$_2$, highlighting interaction effects on quantum Hall phenomena.

Findings

Effective electron mass of 0.8$m_e$ from SdH oscillations.

Zeeman splitting is enhanced by interactions at lower densities.

Quantum Hall states show parity transitions influenced by electron density.

Abstract

We study the magnetotransport of high-mobility electrons in monolayer and bilayer MoSe$_2$, which show Shubnikov-de Haas (SdH) oscillations and quantum Hall states in high magnetic fields. An electron effective mass of 0.8$m_e$ is extracted from the SdH oscillations' temperature dependence; $m_e$ is the bare electron mass. At a fixed electron density the longitudinal resistance shows minima at filling factors (FFs) that are either predominantly odd, or predominantly even, with a parity that changes as the density is tuned. The SdH oscillations are insensitive to an in-plane magnetic field, consistent with an out-of-plane spin orientation of electrons at the $K$-point. We attribute the FFs parity transitions to an interaction enhancement of the Zeeman energy as the density is reduced, resulting in an increased Zeeman-to-cyclotron energy ratio.