Spectroscopic properties of Magnetic Weyl Semimetal

Weyl Semimetals (WSM) are topological materials with broken P or T symmetry Dirac cones and exhibit unusual optical properties. In particular, for Type-II WSM, the anomalous Hall effect enhanced by the large Berry curvature allows for strong gyrotropic and nonreciprocity effects without external magnetic field, which promises potential applications such as nonreciprocal waveguides, optical insulators, etc. However, the experimental realization of WSM device is lacking due to the inadequate permittivity measurements. Here we modeled the permittivity for Type-II WSM with pairs of Weyl nodes, from a linear dispersion Hamiltonian to parametrize the diagonal and gyrotropic term. We performed spectroscopic measurements that take account into the interband and intraband transitions near Weyl nodes. Using the theoretical model and spectroscopic measurements, we were able to obtain key gryotropic parameters of WSMs and gained insights into the electron-photon interactions. Our results are consistent with the theoretical studies of WSMs and experiments of electronic properties including ARPES and Hall measurements.