Galvanomagnetic and Optical Properties of Type-II Weyl Semimetal Candidate WTe₂

Abstract

The galvanomagnetic properties (magnetoresistivity and Hall Effect) and resistivity at temperatures from 2 K to 300 K in magnetic fields of up to 9 T as well as optical characteristics (real and imaginary parts of the complex permittivity, optical conductivity, and reflectivity) at room temperature were studied. It was shown that the temperature dependence of the electrical resistivity has a “metallic” type and is quadratic at low temperatures (< 60 K) that can be caused by the “electron-phonon-surface” interference scattering mechanism in WTe2. Whereas an applied magnetic field induces a minimum in the temperature dependence of the resistivity at low temperatures, that shifts to higher temperature with increasing field, one of the possible explanation of which is the transition from high to weak effective magnetic fields. The magnetoresistivity increases with the magnetic field according to the quadratic law, reaching 1750% at 2 K, which is due to the compensation of charge carriers in WTe2. Hall Effect studies showed that the majority charge carriers are electrons with the concentration 1019 cm-3 and the mobility 7500 cm2/V•s at 2 K. At the same time optical investigations did not reveal the features characteristic of metals. The optical conductivity spectrum is a broad band centered at 3.4 eV, formed by interband transitions. The presence of peaks in the infrared region indicates the formation of low-energy gaps in the band spectrum of WTe2. The obtained data on the real and imaginary parts of the complex permittivity also evidence the absence of a contribution from free carriers up to 0.2 eV. The optical characteristics are shown to be in good agreement with the data on electronic transport properties. The revealed features are a manifestation of the topological nature of the material.