Density functional theory based investigation of heavy fermion band candidates in triplet superconductor UTe2

TL;DR

This study uses density functional theory with a Gutzwiller-like approach to identify and explain the emergence of heavy fermion Fermi surfaces in UTe2, a candidate triplet superconductor, aligning theoretical predictions with experimental observations.

Contribution

It introduces a Gutzwiller-like renormalization in DFT+U calculations to better model heavy fermion Fermi surfaces in UTe2, addressing previous discrepancies.

Findings

Heavy fermion Fermi surface near Z-point identified

Gutzwiller-like renormalization improves experimental agreement

Distortion of f electron band from saddle point to local minimum

Abstract

The compound UTe2 is of great recent interest as a spin triplet superconductor that is thought to realize a topologically nontrivial superconducting order parameter. Though UTe2 is considered to be a heavy fermion material, only light-electron Fermi surfaces have been compellingly identified, while a possible heavy electron Fermi surface near the momentum space Z-point has been the subject of more speculative and incongruent interpretations based on density functional theory (DFT+U) and experimental measurements. Here we explore the DFT+U band structure within a tight binding model framework to identify emergence mechanisms for heavy fermion Fermi surfaces. Applying a Gutzweiller-like renormalization term to f-electron kinetics is found to distort the lowest energy f electron band from a saddle point to a local minimum at the Z-point, introducing a shallow Fermi pocket and greatly improving compatibility with recent experiments.