Temperature Dependence of Charge Transport in an Undoped Weyl Semimetal – Y₂Ir₂O₇

An undoped Weyl Semimetal (WSM) is predicted to exhibit resistivity varying with temperature as ρ α T^-4 in the presence of a random Coulomb potential screened by thermally generated charge carriers. Here we show that, in hydrothermally grown polycrystalline samples of the WSM Y₂Ir₂O₇, ρ = ρ₀T^-4 over four orders of magnitude in ρ. The prefactor, ρ₀, agrees with theoretical estimates within the random potential model using reasonable materials parameters. The model works well beyond its range of applicability, extending into the high-resistivity region where the Ioffe-Regel parameter, k_T l « 2π. The importance of strong electron correlations suggests this is behavior characteristic of a "bad-WSM".