# Magnetoresistance and Quantum Oscillations of an Electrostatically Tuned Semimetal-to-Metal Transition in Ultra-Thin WTe2

## TL;DR

This study demonstrates electrostatic control of magnetoresistance in ultra-thin WTe2, revealing a transition from semimetallic to metallic states with distinct quantum oscillations and a sub-quadratic, density-independent magnetoresistance behavior.

## Contribution

It provides new insights into electrostatically tuning the electronic phases and magnetoresistance in 2D WTe2, including detailed analysis of carrier depletion and quantum oscillations.

## Key findings

- Electrostatic gating switches WTe2 between semimetallic and metallic states.
- Magnetoresistance is large and tunable via doping, with distinct quantum oscillations.
- Magnetoresistance follows a sub-quadratic, density-independent power law.

## Abstract

We report on electronic transport measurements of electrostatically gated nano-devices of the semimetal WTe\textsubscript{2}. High mobility metallic behavior is achieved in the 2D limit by encapsulating thin flakes in an inert atmosphere. At low temperatures, we find that a large magnetoresistance can be turned on and off by electrostatically doping the system between a semimetallic state and an electron-only metallic state, respectively. We confirm the nature of the two regimes by analyzing the magnetoresistance and Hall effect with a two-carrier model, as well as by analysis of Shubnikov-de Haas oscillations, both of which indicate depletion of hole carriers via the electrostatic gate. This confirms that semiclassical transport of two oppositely charged carriers accurately describes the exceptional magnetoresistance observed in this material. Finally, we also find that the magnetoresistance power law is sub-quadratic and density-independent, suggesting new physics specifically in the semimetallic regime.