Evidence for Undoped Weyl Semimetal Charge Transport in a bad Weyl Semi-Metal: Y2Ir2O7

Most Weyl semimetals studied to date either have a chemical potential not situated at the nodal point, or multiple nodal points at different energies, thus leading to metallic behavior in resistivity versus temperature. Undoped Weyl semimetals, in which the chemical potential is exactly at the nodal point will exhibit characteristic non-metallic behavior in transport that should reveal the density of electronic states as well as the dominant scattering mechanisms. We discuss the various types of transport for both doped and undoped Weyl systems. We show that one candidate, Y2Ir2O7, predicted to display a spectrum of an undoped Weyl semimetal, exhibits behavior of a system with the expected quadratic density of states and scattering from charged impurities, namely resistivity varying as 1/T^4 over a large temperature range. We discuss the implications of these results in light of exsiting theories, as well as prospects for future work.