Pressure-enhanced $f$-electron orbital weighting in UTe2 mapped by quantum interferometry

TL;DR

This study investigates how the Fermi surface of UTe$_2$ evolves under pressure using quantum interference oscillations, revealing increased $f$-orbital contribution and continuous Fermi surface warping without reconstruction.

Contribution

It provides the first detailed pressure-dependent mapping of UTe$_2$'s Fermi surface and links increased $f$-orbital contribution to pressure-induced changes in electronic structure.

Findings

Fermi surface remains continuous up to 19.5 kbar with no reconstruction.

Fermi sheet warping increases smoothly with pressure.

Enhanced $f$-orbital contribution correlates with increased warping.

Abstract

The phase landscape of UTe$_2$ features a remarkable diversity of superconducting phases under applied pressure and magnetic field. Recent quantum oscillation studies at ambient pressure have revealed the quasi-2D Fermi surface of this material. However, the pressure-dependence of the Fermi surface remains an open question. Here we track the evolution of the UTe$_2$ Fermi surface as a function of pressure up to 19.5 kbar by measuring quantum interference oscillations. We find that in sufficient magnetic field to suppress both superconductivity at low pressures and incommensurate antiferromagnetism at higher pressures, the quasi-2D Fermi surface found at ambient pressure smoothly connects to that at 19.5 kbar, with no signs of a reconstruction over this pressure interval. We observe a smooth increase in oscillatory frequency with increasing pressure, indicating that the warping of the cylindrical Fermi sheets continuously increases with pressure. By computing a tight-binding model, we show that this enhanced warping indicates increased $f$-orbital contribution at the Fermi level - up to and beyond the critical pressure at which superconductivity is truncated. These findings highlight the value of high-pressure quantum interference measurements as a new probe of the electronic structure in heavy fermion materials.