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

The galvanomagnetic properties [magnetoresistivity (MR) and Hall Effect] and resistivity at temperatures from 2 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 WTe
₂
. Whereas an applied magnetic field induces a minimum in the temperature dependence of the resistivity at low temperatures that shifts to a higher temperature with increasing field, one of the possible explanation of which is the transition from high to weak effective magnetic fields. The MR 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 WTe
₂
. The Hall effect studies showed that the majority charge carriers are electrons with the concentration of
$\sim 10^{19}$
cm
⁻³
and mobility of 7500 cm
²
/
$\text{V}\cdot \text{s}$
at 2 K. At the same time, optical investigations did not reveal the feature characteristics of metals. The optical conductivity spectrum is a broadband centered at 3.4 eV and formed by interband transitions. The presence of peaks in the infrared region indicates the formation of low-energy gaps in the band spectrum of WTe
₂
. 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.