Measurement of Conduction and Valence Bands g-factors in a Transition Metal Dichalcogenide Monolayer

TL;DR

This paper introduces a novel optical method to accurately measure the separate g-factors of conduction and valence bands in monolayer transition-metal dichalcogenides, providing essential data for understanding their magnetic properties.

Contribution

The paper presents an original optical technique that isolates and measures the individual conduction and valence band g-factors in monolayer WSe2, overcoming previous experimental limitations.

Findings

Measured conduction band g-factors: gc1=0.86, gc2=3.84

Measured valence band g-factor: gv=6.1

Method enables direct and accurate g-factor determination

Abstract

The electron valley and spin degree of freedom in monolayer transition-metal dichalcogenides can be manipulated in optical and transport measurements performed in magnetic fields. The key parameter for determining the Zeeman splitting, namely the separate contribution of the electron and hole g-factor, is inaccessible in most measurements. Here we present an original method that gives access to the respective contribution of the conduction and valence band to the measured Zeeman splitting. It exploits the optical selection rules of exciton complexes, in particular the ones involving inter-valley phonons, avoiding strong renormalization effects that compromise single particle g-factor determination in transport experiments. These studies yield a direct determination of single band g factors. We measure gc1= 0.86, gc2=3.84 for the bottom (top) conduction bands and gv=6.1 for the valence band of monolayer WSe2. These measurements are helpful for quantitative interpretation of optical and transport measurements performed in magnetic fields. In addition the measured g-factors are valuable input parameters for optimizing band structure calculations of these 2D materials.