We study the linear response of doped three-dimensional Dirac and Weyl semimetals to vector potentials, by calculating the wave-vector- and frequency-dependent current-current response function analytically. The longitudinal part of the dynamic current-current response function is then used to study the plasmon dispersion and the optical conductivity. The transverse response in the static limit yields the orbital magnetic susceptibility. In a Weyl semimetal, along with the current-current response function, all these quantities are significantly impacted by the presence of parallel electric and magnetic fields (a finite $\mathbf{E}·\mathbf{B}$ term) and can be used to experimentally explore the chiral anomaly.

• Received 2 July 2017

DOI:https://doi.org/10.1103/PhysRevB.97.035403