Field-reentrant superconductivity close to a metamagnetic transition in the heavy-fermion superconductor UTe2

07 January 2020 par Super Administrateur
Georg Knebel, William Knafo, Alexandre Pourret, Qun Niu, Michal Vališka, Daniel Braithwaite, Gérard Lapertot, Marc Nardone, Abdelaziz Zitouni, Sanu Mishra, Ilya Sheikin, Gabriel Seyfahrt, Jean-Pascal Brison, Dai Aoki, Jacques Flouquet

They present a study of the upper critical field of the newly discovered heavy fermion superconductor UTe2 by magnetoresistivity measurements in pulsed magnetic fields up to 60~T and static magnetic fields up to 35~T. We show that superconductivity survives up to the metamagnetic transition at Hm≈35~T at low temperature. Above Hm superconductivity is suppressed. At higher temperature superconductivity is enhanced under magnetic field leading to reentrance of superconductivity or an almost temperature independent increase of Hc2. By studying the angular dependence of the upper critical field close to the b axis (hard magnetization axis) we show that the maximum of the reentrant superconductivity temperature is depinned from the metamagnetic field. A key ingredient for the field-reinforcement of superconductivity on approaching Hm appears to be an immediate interplay with magnetic fluctuations and a possible Fermi-surface reconstruction.

Upper critical field of UTe2


Journal of the Physical Society of Japan, June 15, 2019, Vol. 88, No. 6