Novel anisotropic optical THz response of TaAs

We present the first characterization of the full anisotropic optical response of the Weyl semimetal TaAs at far-IR frequencies, obtained by taking polarization-dependent Fourier transform infrared spectroscopy measurements on the (112) surface of a TaAs crystal. This is the first clear characterization of the optical for polarization both in the ab−plane and along the c−axis. These measurements characterize the band anisotropy of the Weyl pockets in TaAs which yields interesting insights into the potential implication of past characterizations of the optical for polarization in the ab-plane. Hyperbolic plasmonic dispersion at THz frequencies is also observed.