Optical conductivity of the type-II Weyl semimetal WTe2 under pressure

Tungsten ditelluride ${\mathrm{WTe}}₂$ is a type-II Weyl semimetal with electronic properties highly sensitive to external pressure, as demonstrated by the superconductivity emerging under pressure. Here we study the optical conductivity of the type-II Weyl semimetal ${\mathrm{WTe}}₂$ under external pressure at room temperature. With increasing pressure, a pronounced spectral weight transfer occurs from the high-energy to the low-energy interband transitions, with drastic changes in the profile of the optical conductivity spectrum indicating a high sensitivity of the electronic band structure to external pressure. The detailed analysis of the pressure-dependent optical conductivity furthermore reveals anomalies at the pressures $\ensuremath{\sim}2$ and $\ensuremath{\sim}4.5\phantom{\rule{4pt}{0ex}}\mathrm{GPa}$, where an electronic and a structural phase transition, respectively, were reported in the literature.