Pair Wavefunction Symmetry in UTe2 from Zero-Energy Surface State Visualization

Abstract

Although nodal spin-triplet topological superconductivity appears probable in UTe2, its superconductive order-parameter ${\Delta }_k$ remains unestablished. In theory, a distinctive identifier would be the existence of a superconductive topological surface band (TSB), which could facilitate zero-energy Andreev tunneling to an s-wave superconductor, and also distinguish a chiral from non-chiral ${\Delta }_k$ via enhanced s-wave proximity. Here we employ s-wave superconductive scan-tips and detect intense zero-energy Andreev conductance at the UTe2 (0-11) termination surface. Imaging reveals sub-gap quasiparticle scattering interference signatures with a-axis orientation. The observed zero-energy Andreev peak splitting with enhanced s-wave proximity, signifies that ${\Delta }_k$ of UTe2 is a non-chiral state: B1u, B2u or B3u. However, if the quasiparticle scattering along the a-axis is internodal, then a non-chiral B3u state is the most consistent for UTe2.

45 pages, 5 figures, to appear in Science (2025)

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• Multiple phases in K2Cr3As3: a playground for manipulating topological superconductivity
• Visualizing the Odd-parity Superconducting Order Parameter and its Quasiparticle Surface Band in UTe2
• Evidence of intertwined pair density and charge density wave orders in UTe2
• Raman response of collective modes in multicomponent superconductors
• Unconventional superconductivity emerging along with the strange-metal behavior in UAs2 under pressure