Limited coincidence between ultrahigh-field superconductivity and line of metamagnetic endpoints in UTe$_2$

TL;DR

This study investigates the relationship between superconductivity and metamagnetic transitions in UTe$_2$, revealing limited coincidence and angular dependence of these phenomena under high magnetic fields.

Contribution

It provides detailed measurements of magnetization and conductivity, showing that superconductivity and metamagnetic phases are not directly aligned and vary with field orientation.

Findings

Superconducting region extends narrowly near the metamagnetic boundary.

Magnetization jumps vanish away from the $b$ axis.

Superconductivity persists beyond 73 T near the $ab$ plane.

Abstract

The field-dependent magnetization of UTe$_2$ was measured through the metamagnetic transition at a variety of field angles, tracking how the step in magnetization evolves with fields tilted away from the $b$ axis. For fields oriented within the $ab$ plane, jumps in both $M_a$ and $M_b$ vanish approximately 18{\deg} away from the $b$ axis. From contactless conductivity measurements, we find that the halo-like high-field superconducting region extends to the $ab$ plane, where it exists only within a very narrow ($<$1{\deg}) angular range near the termination of the metamagnetic phase boundary and extends beyond the highest measured field of 73 T. As the field orientation tilts towards the $c$ axis, the superconducting and metamagnetic phase boundaries no longer coincide and exhibit distinct trends.