Odd-Parity Quasiparticle Interference in the Superconductive Surface State of UTe2

Kavli Affiliate: J. C. Seamus Davis

| First 5 Authors: Shuqiu Wang, Kuanysh Zhussupbekov, Joseph P. Carroll, Bin Hu, Xiaolong Liu

| Summary:

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.

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