Mapping the rich superconducting phase diagram of ultraclean UTe₂

The odd-parity superconductor candidate UTe₂ hosts a wealth of exotic physical phenomena, including a variety of superconducting phases. Three distinct superconducting states have been observed at ambient pressure in high magnetic field experiments, while up to five separate superconducting phases have been reported from hydrostatic pressure measurements. This talk will discuss the phase diagram of UTe₂ as measured on a new generation of pristine quality samples grown by a salt flux technique. I will outline our recent measurements – to high magnetic fields at ambient pressure and under hydrostatic pressures in ambient field – that reveal notable similarities and differences between the phase boundaries identified by our study with those reported from measurements on numerous samples of varying disorder level. The talk will conclude with a discussion on how the responses of different superconducting phase boundaries to varying levels of disorder in UTe₂ can shed light on understanding their microscopic pairing mechanisms.