The heavy fermion superconductor UTe₂ has attracted widespread interest due to its remarkably large upper critical fields and negligible NMR Knight shift change at T_c, pointing to an odd-parity spin-triplet pairing mechanism. The UTe₂ phase diagram exhibits three distinct superconducting phases depending on the tilt-angle of the magnetic field, including a very high field superconducting state that extends to fields > 70 T. An optimised crystal growth technique, pioneered by synthesis groups in Tohoku and Prague, has recently produced a new generation of high-quality crystals.  This talk will review our recent measurements of UTe₂ in high magnetic fields. Increased sample quality has enabled us to measure de Haas-van Alphen effect quantum oscillations, to map the Fermi surface [1]. Furthermore, through combining experiments up to 41 T in steady fields with pulsed field measurements to 85 T, we have uncovered an extended region of quantum criticality anchoring the high magnetic field superconducting phase landscape of UTe₂ [2]. 

Refences:

[1] Eaton et al, Nat. Commun. 2024
[2] Wu et al, arXiv:2403.02535