Odd-Parity Quasiparticle Interference in the Superconductive Surface State of UTe2
Shuqiu Wang, Kuanysh Zhussupbekov, Joseph P. Carroll, Bin Hu, Xiaolong Liu, Emile Pangburn, Adeline Crepieux, Catherine Pepin, Christopher Broyles, Sheng Ran, Nicholas P. Butch, Shanta Saha, Johnpierre Paglione, Cristina Bena, J. C. Séamus Davis, Qiangqiang Gu
Published: 2025/3/22
Abstract
Although no known material exhibits intrinsic topological superconductivity, wherein spin-triplet odd-parity electron pairing occurs, UTe2 is now the leading representative of this class. Conventionally, the parity of the superconducting order parameter may be established by using Bogoliubov quasiparticle interference (QPI) imaging. However, odd-parity superconductors should support a topological quasiparticle surface band (QSB) at energies within the maximum superconducting energy gap. QPI would then be dominated by the electronic structure of the QSB and only reveal the characteristics of the bulk order parameter excursively. Here, we visualize quasiparticle interference patterns of UTe2 and find that, at the (0-11) cleave surface, a new band of Bogoliubov quasiparticles appears only in the superconducting state. QPI visualization then allows study of dispersion of states within this QSB, which we demonstrate exists only within the range of Fermi momenta projected onto the (0-11) surface. Finally, we develop a theoretical framework to predict the QPI signatures of such a QSB at the (0-11) surface of UTe2. Its predictions are most consistent with the experimental results if the bulk superconducting gap function exhibits time-reversal conserving, odd-parity, a-axis nodal, B3u symmetry.