Suppressed magnetic scattering sets conditions for the emergence of 40 T high-field superconductivity in UTe2

Abstract

The potential spin-triplet heavy-fermion superconductor UTe2 exhibits signatures of multiple distinct superconducting phases. For field aligned along the b axis a metamagnetic transition occurs at μ0Hm ≈ 35 T. It is associated with a spin reorientation inducing magnetic fluctuations that may be beneficial for the field-enhanced superconductivity surviving up to Hm. Once the field is tilted away from the b towards the c axis, a re-entrant superconducting phase emerges just above Hm(θ). However, under pressure this phase detaches from Hm. In order to better understand this remarkably field-resistant phase we investigate magnetic torque and electrical magnetotransport in pulsed magnetic fields. The observed zero-Hall signal evidences the superconducting nature of this distinct high-field phase. We determine its record-breaking upper critical field of μ0Hc2 ≈ 75 T. Furthermore, we provide evidence for a strong angle-dependent reduction of magnetic scattering, likely accompanied by changes in the electronic band structure induced by the tilted field.

A review of UTe2at high magnetic fields

“…A recent preprint reports magnetocaloric measurements that indicate SC FP is indeed a bulk superconducting phase [61]. A separate preprint reports that the normal-state Hall effect in the FP state is related to the SC FP phase, with the Hall effect almost entirely suppressed where the SC FP phase is most robust [76]. The authors hypothesize that this could be due to compensation from an internal exchange field, as required for the Jaccarino-Peter mechanism described in section 3.5.5.…”