Quasi-2D Fermi surface in the anomalous superconductor UTe2

TL;DR

This study reveals that UTe2 has a quasi-2D Fermi surface composed of two cylindrical sheets, providing insights into its spin-triplet superconductivity and constraining the possible symmetry of its order parameter.

Contribution

The paper provides the first direct measurement of UTe2's Fermi surface, showing a quasi-2D structure with two cylindrical sheets, advancing understanding of its unconventional superconductivity.

Findings

UTe2 has a quasi-2D Fermi surface.

The Fermi surface consists of two cylindrical sheets of electron- and hole-type.

No evidence of 3D Fermi surface sections was found.

Abstract

The heavy fermion paramagnet UTe$_2$ exhibits numerous characteristics of spin-triplet superconductivity. Efforts to understand the microscopic details of this exotic superconductivity have been impeded by uncertainty regarding the underlying electronic structure. Here we directly probe the Fermi surface of UTe$_2$ by measuring magnetic quantum oscillations in pristine quality crystals. We find an angular profile of quantum oscillatory frequency and amplitude that is characteristic of a quasi-2D Fermi surface, which we find is well described by two cylindrical Fermi sheets of electron- and hole-type respectively. Additionally, we find that both cylindrical Fermi sheets possess considerable undulation but negligible small-scale corrugation, which may allow for their near-nesting and therefore promote magnetic fluctuations that enhance the triplet pairing mechanism. Importantly, we find no evidence for the presence of any 3D Fermi surface sections. Our results place strong constraints on the possible symmetry of the superconducting order parameter in UTe$_2$.