Electron-Hole Scattering Dichotomy and Anisotropic Warping in Quasi-Two-Dimensional Fermi Surfaces of UTe2

TL;DR

This study combines experimental and theoretical methods to elucidate the Fermi surface geometry of UTe2, revealing anisotropic warping and a significant electron-hole scattering dichotomy that impacts its superconducting properties.

Contribution

It provides the first detailed mapping of UTe2's quasi-two-dimensional Fermi surface and links anisotropic scattering and magnetic fluctuations to its superconductivity mechanism.

Findings

Q2D Fermi surface has a rectangular shape with anisotropic warping.

Electron quasiparticles have shorter lifetimes than hole quasiparticles.

Magnetic fluctuations enhance scattering on electron pockets, influencing superconductivity.

Abstract

We present a combined experimental and theoretical study of the detailed Fermi-surface (FS) geometry of UTe2, a heavy-fermion superconductor that has recently attracted considerable attention as a promising candidate for spin-triplet pairing. Using angle-dependent magnetoresistance oscillations, a bulk- and low-energy-sensitive transport probe for quasi-two-dimensional (Q2D) electronic structures, we directly determine the in-plane FS geometry. We found that the Q2D FS exhibits a rectangular cross-sectional shape with strongly anisotropic warping, originating from the hybridization of two orthogonal quasi-one-dimensional bands. Through a quantitative comparison between experiment and theoretical calculations, we further reveal a large electron-hole scattering dichotomy: the quasiparticle lifetime on the electron FS is substantially shorter than that on the hole FS. This dichotomy is naturally explained by anisotropic, low-dimensional antiferromagnetic fluctuations, which selectively enhance scattering on the electron FS. This suggests a dominant role of the electron pockets for the emergence of superconductivity. Our results clarify a direct relation between FS geometry, magnetic fluctuations, and momentum-dependent quasiparticle lifetimes, and thus providing a crucial basis for the microscopic understanding of pairing mechanism, and impose stringent constraints on the gap symmetry of spin-triplet superconductivity in UTe2.