Electronic transport and optical properties of Mo_0.5W_0.5Te₂ single crystal

A relatively pure and perfect Weyl semimetal Mo_0.5W_0.5Te₂ single crystal was synthesized, and its electrical resistivity, galvanomagnetic properties at temperatures from 4.2 to 80 K in fields up to 10 T, as well as optical properties at room temperature were studied. It is shown that the temperature dependence of the resistivity has a metallic type. At T = 4.2 K and in a 10 T field, the magnetoresistance reaches 29%, monotonously decreasing with temperature. Analysis of the field and temperature dependences of the magnetoresistance suggests that the Fermi surface of Mo_0.5W_0.5Te₂ can contain both open and closed sheets. Studies of the Hall effect and estimates made on this basis showed that the main charge carriers are electrons with a concentration of ∼ 10²⁰ cm^-3 and mobility of ∼ 151 cm²/V.s at T = 4.2 K. With an increase in temperature, the concentration of current carriers increases, and their mobility decreases. Optical studies demonstrate that the Mo_0.5W_0.5Te₂ single crystal has no features typical of metals. Interband absorption of light dominates over the entire studied spectral region. The appearance of a weak contribution from free carriers is noted at energies of less than 0.6 eV.