Field-induced compensation of magnetic exchange as the possible origin of reentrant superconductivity in UTe2
Toni Helm, Motoi Kimata, Kenta Sudo, Atsuhiko Miyata, Julia Stirnat, Tobias Förster, J. Hornung, Markus König, I. Sheikin, Alexandre Pourret, G. Lapertot, Dai Aoki, G. Knebel, J. Wosnitza, Jean‐Pascal Brison
Abstract
Abstract The potential spin-triplet heavy-fermion superconductor UTe 2 exhibits signatures of multiple distinct superconducting phases. For field aligned along the b axis, a metamagnetic transition occurs at μ 0 H m ≈ 35 T. It is associated with magnetic fluctuations that may be beneficial for the field-reinforced superconductivity surviving up to H m . Once the field is tilted away from the b towards the c axis, a reentrant superconducting phase emerges just above H m . In order to better understand this remarkably field-resistant superconducting phase, we conducted magnetic-torque and magnetotransport measurements in pulsed magnetic fields. We determine the record-breaking upper critical field of μ 0 H c2 ≈ 73 T and its evolution with angle. Furthermore, the normal-state Hall effect experiences a drastic suppression indicative of a reduced band polarization above H m in the angular range around 30° caused by a partial compensation between the applied field and an exchange field. This promotes the Jaccarino-Peter effect as a likely mechanism for the reentrant superconductivity above H m .