Quantum oscillation study of the large magnetoresistance in Mo substituted WTe$_2$ single crystals

TL;DR

This study investigates how Mo substitution affects quantum oscillations and magnetoresistance in WTe$_2$, revealing that decreased MR is due to reduced mobility despite improved charge compensation.

Contribution

It provides new insights into the effects of Mo substitution on quantum oscillations and magnetoresistance, challenging previous charge imbalance explanations.

Findings

MR decreases with Mo substitution

Charge compensation improves with Mo substitution

Transport mobility decreases despite better charge compensation

Abstract

The list of interesting electrical properties exhibited by transition metal dichalcogenides has grown with the discovery of extremely large magnetoresistance (MR) and type-II Weyl semimetal behaviour in WTe$_2$ and MoTe$_2$. The extremely large MR in WTe$_2$ is still not adequately understood. Here, we systematically study the effect of Mo substitution on the quantum oscillations in the MR in WTe$_2$. The MR decreases with Mo substitution, however, the carrier concentrations extracted from the quantum oscillations show that the charge compensation improves. We believe that earlier interpretations based on the two-band theory, which attribute the decrease in MR to charge imbalance, could be incorrect due to over-parametrization. We attribute the decrease in MR in the presence of charge compensation to a fall in transport mobility, which is evident from the residual resistivity ratio data. The quantum scattering time and the effective masses do not change within experimental errors upon substitution.