C -axis electrical transport at the metamagnetic transition in the heavy-fermion superconductor UTe2 under pressure

Abstract

The electrical resistivity of the unconventional superconductor UTe2 shows very anisotropic behavior in the normal state depending on the current direction. In this paper we show that the maximum in the resistivity ρc for current applied along the c axis at Tρcmax≈14.75 K follows the minimum in the thermal expansion Tα★ along the b axis. Under a magnetic field applied along the b axis, Tρcmax can be tracked up to the critical point of the first-order metamagnetic transition, which is located near 6 K and 34.5 T. Surprisingly, at the metamagnetic field Hm the resistivity ρc shows a steplike decrease while the resistivities ρa and ρb, for current along the a and b axes, respectively, show a steplike increase. Under hydrostatic pressure Tρcmax and Hm decrease significantly up to the critical pressure pc at which superconductivity is suppressed and a long-range antiferromagnetic order appears. We show that the phase diagram at different pressures can be scaled by Tρcmax in field and temperature, suggesting that this temperature scale is governing the main interactions in the normal state.