Pair wave function symmetry in UTe <sub>2</sub> from zero-energy surface state visualization
Qiangqiang Gu, Shuqiu Wang, Joseph P. Carroll, Kuanysh Zhussupbekov, Christopher Broyles, Sheng Ran, Nicholas P. Butch, Jarryd A. Horn, Shanta Saha, Johnpierre Paglione, Xiaolong Liu, J. C. Davis, Dung‐Hai Lee
Abstract
Although nodal spin-triplet topological superconductivity appears probable in uranium ditelluride (UTe 2 ), its superconductive order parameter Δ k remains unestablished. In theory, a distinctive identifier would be the existence of a superconductive topological surface band, which could facilitate zero-energy Andreev tunneling to an s-wave superconductor and also distinguish a chiral from a nonchiral Δ k through enhanced s-wave proximity. In this study, we used s-wave superconductive scan tips and detected intense zero-energy Andreev conductance at the UTe 2 (0-11) termination surface. Imaging revealed subgap quasiparticle scattering interference signatures with a -axis orientation. The observed zero-energy Andreev peak splitting with enhanced s-wave proximity signifies that Δ k of UTe 2 is a nonchiral state: B 1 u , B 2 u , or B 3 u . However, if the quasiparticle scattering along the a axis is internodal, then a nonchiral B 3 u state is the most consistent for UTe 2 .