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

Abstract

The electrical resistivity of the unconventional superconductor UTe${}_2$ shows very anisotropic behavior in the normal state depending on the current direction. In the present paper we show that the maximum in the resistivity $\ddot{I}{}_c$ for current applied along the $c$ axis at $T_{\ddot{I}{}_c}^{\max }\approx 14.75$~K follows the minimum in the thermal expansion $T_{\hat{I}}{\pm }^{\star }$ along $b$ axis. Under a magnetic field applied along the $b$ axis, $T_{\ddot{I}{}_c}^{\max }$ 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 $H_m$ the resistivity $\ddot{I}{}_c$ shows a steplike decrease while the resistivities $\ddot{I}{}_a$ and $\ddot{I}{}_b$, for current along the $a$ and $b$ axis, respectively, show a steplike increase. Under hydrostatic pressure $T_{\ddot{I}{}_c}^{\max }$ and $H_m$ decrease significantly up to the critical pressure $p_c$ 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 $T_{\ddot{I}{}_c}^{\max }$ in field and temperature suggesting that this temperature scale is governing the main interactions in the normal state.

accepted in Phys. Rev. B