c-axis transport in UTe2: Evidence of three-dimensional conductivity component

Here we study the temperature dependence of electrical resistivity for currents directed along all crystallographic axes of the spin-triplet superconductor UTe₂. We focus particularly on an accurate determination of the resistivity along the c axis (ρ_c) by using a generalized Montgomery technique that allows extraction of crystallographic resistivity components from a single sample. In contrast to expectations from the observed highly anisotropic band structure, our measurement of the absolute values of resistivities in all current directions reveals a surprisingly nearly isotropic transport behavior at temperatures above Kondo coherence, with ρ_c ~ ρ_b ~ 2 ρ_a, that evolves to reveal qualitatively distinct behaviors on cooling. The temperature dependence of ρ_c exhibits a peak at a temperature much lower than the onset of Kondo coherence observed in ρ_a and ρ_b, consistent with features in magnetotransport and magnetization that point to a magnetic origin. A comparison to the temperature-dependent evolution of the scattering rate observed in angle-resolved photoemission spectroscopy experiments provides important insights into the underlying electronic structure necessary for building a microscopic model of superconductivity in UTe₂.