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

## TL;DR

This paper uses quantum interferometry to study how pressure affects the electronic structure of UTe2, a heavy fermion superconductor.

## Contribution

The study reveals that pressure increases f-orbital contributions to the Fermi surface without causing a reconstruction.

## Key findings

- Quantum interference oscillations show a smooth increase in Fermi surface warping with pressure.
- The Fermi surface remains quasi-2D and continuous under pressure up to 19.5 kbar.
- Increased f-orbital contribution is observed at the Fermi level even beyond the superconducting transition.

## Abstract

The phase landscape of UTe2 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 UTe2 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 sensitive probe of the electronic structure in heavy fermion materials.

The discovery of superconductivity in the heavy fermion compound UTe2, a potential topological and triplet-paired superconductor, has generated significant interest in condensed matter physics with particular interest in the nature of the Fermi surface. Here, the authors employed a contactless conductivity technique to investigate the quantum interference oscillations of compressed UTe2 up to 19.5 kbar, aiming to examine key features of its Fermi surface.