Yin-Yang vortex on UTe<sub>2</sub> (011) surface.

Yin, Ruotong; Li, Yuanji; Du, Zengyi; Yuan, Dengpeng; Wang, Shiyuan; Gong, Jiashuo; Li, Mingzhe; Chen, Ziyuan et al. · Nat Commun · 2026

basic_science · Level V

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Abstract

UTe<sub>2</sub> is a candidate spin-triplet superconductor, yet its superconducting state remains debated. Using scanning tunneling microscopy/spectroscopy, we observe a novel magnetic vortex with distinct dark-bright contrast in local density of states on UTe<sub>2</sub> (011) surface under perpendicular magnetic fields, resembling the Yin-Yang diagram in Taoism. Each vortex carries a quantized magnetic flux, and the boundary between the two parts aligns with crystallographic a-axis. The vortex states exhibit intriguing behaviors -- the Yang part exhibits a sharp zero-energy conductance peak, whereas the Yin part shows a superconducting gap with pronounced coherence peaks, sharper than those without fields. Theoretical analysis attributes this pattern to vortex-induced asymmetric suppression of topological surface states caused by the tilted Fermi surface, constraining possible d-vector orientations. Our findings constitute distinctive evidence for spin-triplet pairing in UTe<sub>2</sub>, and provide new avenues for exploring the interplay between surface states and vortex-bound states in topological superconductors.