Chiral superconductivity in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>UTe</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math> via emergent <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>C</mml:mi><mml:mn>4</mml:mn></mml:msub></mml:math> symmetry and spin-orbit coupling
Daniel Shaffer, Dmitry V. Chichinadze
Abstract
A lot of attention has been drawn to superconductivity in ${\mathrm{UTe}}_{2}$, with suggestions of time-reversal symmetry-breaking triplet chiral superconducting order parameter. The chirality of the order parameter has been attributed to an accidental near degeneracy of two superconducting components belonging to one-dimensional (1D) irreducible representations (irreps) ${B}_{2u}$ and ${B}_{3u}$ of the relevant ${D}_{2h}$ point group, and it has been argued that the chiral ${B}_{2u}+i{B}_{3u}$ combination is selected by ferromagnetic fluctuations. In this work we present a possible explanation of the near degeneracy as a result of an accidental ${C}_{4}$ symmetry of the band structure, with the superconducting order parameter belonging to the 2D ${E}_{u}$ irrep of ${D}_{4h}$ that uniquely descends to the sought-after ${B}_{2u}+i{B}_{3u}$ combination. We show that the ${C}_{4}$ symmetry is emergent at the level of the interactions using a renormalization group calculation and argue that the chiral combination of the order parameter is favored when spin-orbit coupling is added to the model.