The Fermi surface of UTe₂

Magnetic quantum oscillations are a powerful, direct probe of the Fermi surface of materials. This talk will discuss recent experimental studies of quantum oscillations in the magnetization and electrical conductivity of UTe₂. de Haas-van Alphen effect measurements at dilution fridge temperatures in intermediate magnetic fields have revealed the presence of two quasi-2D cylindrical Fermi sheets with strongly renormalized carrier masses (~40 m_e) [arXiv:2302.04758]. At high magnetic fields oscillations in the conductivity have been observed, which possess markedly different frequencies and temperature dependences than those seen in the de Haas-van Alphen effect. By comparing our magnetoconductance measurements up to 70 T with a geometrical model of the UTe₂ Fermi surface, we find that these oscillations can be well described by a quantum interference effect from quasiparticles tunnelling between the quasi-2D Fermi sheets at high fields [arXiv:2307.00568]. A discussion will be made of how the recent determination of the Fermi surface geometry may help lead towards a microscopic understanding of the exotic superconducting pairing mechanism(s) at play in UTe₂.