Directional dark matter detection in anisotropic Dirac materials

Dirac materials, because of their small ${\cal O}(\mbox{meV})$ band gap, are a promising target for dark photon-mediated scattering and absorption light matter. In this paper, we characterize the daily modulation rate matter interacting with material due to anisotropies in crystal structure. We show that is an O}(1)$ fraction total ZrTe$_5$. When present, dominated by orientation material's dielectric tensor respect wind, maximized when oriented such wind completely aligned largest smallest components at two different times day. Because large modulation, any putative signal could be rapidly verified or ruled out changing observing how pattern changes.