Periodic Anderson model for magnetism and superconductivity in UTe2

TL;DR

This paper develops a detailed periodic Anderson model for UTe2, explaining its magnetism and superconductivity, and predicts various phases including a mixed-parity state with broken inversion symmetry.

Contribution

It introduces a 24-band tight-binding model consistent with experimental data and explores pressure and magnetic field effects on superconducting and magnetic phases.

Findings

Coulomb interactions enhance Ising ferromagnetic fluctuations.

Pressure induces a transition to antiferromagnetic fluctuations and spin-singlet superconductivity.

A phase diagram with multiple superconducting phases and a spontaneous inversion symmetry breaking state.

Abstract

We provide and analyze a periodic Anderson model for studying magnetism and superconductivity in UTe$_2$, a recently-discovered candidate for a topological spin-triplet superconductor. The 24-band tight-binding model reproduces the band structure obtained from a DFT$+U$ calculation consistent with an angle-resolved photoemission spectroscopy. The Coulomb interaction of $f$-electrons enhances Ising ferromagnetic fluctuation along the $a$-axis and stabilizes spin-triplet superconductivity of either $B_{3u}$ or $A_{u}$ symmetry. When effects of pressure are taken into account in hopping integrals, the magnetic fluctuation changes to antiferromagnetic one, and accordingly spin-singlet superconductivity of $A_{g}$ symmetry is stabilized. Based on the results, we propose pressure-temperature and magnetic field-temperature phase diagrams revealing multiple superconducting phases as well as an antiferromagnetic phase. In particular, a mixed-parity superconducting state with spontaneous inversion symmetry breaking is predicted.