Non-stoichiometry effects on the extreme magnetoresistance in Weyl semimetal WTe2

TL;DR

This study systematically investigates how non-stoichiometry, specifically Te vacancies, affects the extreme magnetoresistance in WTe2, revealing that electron doping and mobility are key factors.

Contribution

It demonstrates the impact of Te vacancy-induced non-stoichiometry on magnetoresistance and elucidates the roles of electron-hole balance and mobility in WTe2.

Findings

Magnetoresistance depends strongly on residual resistivity ratio.

Te vacancies cause electron doping, disrupting carrier balance.

High mobility and compensation are crucial for extreme magnetoresistance.

Abstract

Non-stoichiometry effect on the extreme magnetoresistance is systematically investigated for the Weyl semimetal WTe2. Magnetoresistance and Hall resistivity are measured for the as-grown samples with a slight difference in Te vacancies and the annealed samples with increased Te vacancies. The fittings to a two-carrier model show that the magnetoresistance is strongly dependent on the residual resistivity ratio (i.e., the degree of non-stoichiometry), which is eventually understood in terms of electron doping which not only breaks the balance between electron-type and hole-type carrier densities but also reduces the average carrier mobility. Thus, compensation effect and ultrahigh mobility are probably the main driving force of the extreme magnetoresistance in WTe2.