Fermi surface study of the putative spin-triplet superconductor UTe₂

The unconventional superconductor UTe₂ exhibits numerous properties indicative of spin-triplet pairing, including an upper critical field far in excess of the Pauli paramagnetic limit, and re-entrant superconductivity at high magnetic fields > 40 T. However, a detailed understanding of the material's Fermi surface remains a key open question hampering efforts to attain a more detailed theoretical picture of the microscopic pairing mechanism(s) at play.

Here, we report a detailed de Haas-van Alphen study of the Fermi surface of UTe₂. We measured quantum oscillations in the magnetic torque and contactless resistivity of several high quality samples (RRR ~ 900, Tc = 2.1 K) in a dilution refrigerator at temperatures down to 19 mK and magnetic fields up to 28 T, through two orthogonal rotation planes. Importantly, access to field strengths this high allowed us to measure directly along the [001] direction, which has previously been proposed to run parallel to the axis of cylindrical Fermi surface sections.

We present a summary of our angle- and temperature-dependent results performed to date, and compare to DFT and DMFT calculations that we find to capture the majority of the observed behavior.