<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>c</mml:mi></mml:math>-axis electrical transport at the metamagnetic transition in the heavy-fermion superconductor <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>UTe</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math> under pressure
G. Knebel, Alexandre Pourret, S. Rousseau, Nils Marquardt, D. Braithwaite, Fuminori Honda, Dai Aoki, G. Lapertot, W. Knafo, G. Seyfarth, Jean‐Pascal Brison, J. Flouquet
Abstract
The electrical resistivity of the unconventional superconductor ${\mathrm{UTe}}_{2}$ shows very anisotropic behavior in the normal state depending on the current direction. In this paper we show that the maximum in the resistivity ${\ensuremath{\rho}}_{c}$ for current applied along the $c$ axis at ${T}_{{\ensuremath{\rho}}_{c}}^{\mathrm{max}}\ensuremath{\approx}14.75$ K follows the minimum in the thermal expansion ${T}_{\ensuremath{\alpha}}^{★}$ along the $b$ axis. Under a magnetic field applied along the $b$ axis, ${T}_{{\ensuremath{\rho}}_{c}}^{\mathrm{max}}$ 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 ${\ensuremath{\rho}}_{c}$ shows a steplike decrease while the resistivities ${\ensuremath{\rho}}_{a}$ and ${\ensuremath{\rho}}_{b}$, for current along the $a$ and $b$ axes, respectively, show a steplike increase. Under hydrostatic pressure ${T}_{{\ensuremath{\rho}}_{c}}^{\mathrm{max}}$ 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 ${T}_{{\ensuremath{\rho}}_{c}}^{\mathrm{max}}$ in field and temperature, suggesting that this temperature scale is governing the main interactions in the normal state.