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TT: Fachverband Tiefe Temperaturen
TT 29: Unconventional Superconductors
TT 29.2: Talk
Tuesday, March 10, 2026, 09:45–10:00, CHE/0091
Determining the superconducting order parameter of UPt3 using scanning tunneling microscopy — •Rebecca Bisset1, Luke C. Rhodes1, Hugo Decitre1, Matthew Neat1, Ana Maldonado1, Andrew Huxley2, Carolina A. Marques1, and Peter Wahl1,3 — 1SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS, United Kingdom — 2SUPA, School of Physics and Astronomy, University of Edinburgh, Kings Buildings, Edinburgh, EH9 3FD, United Kingdom — 3Physikalisches Institut, Universität Bonn, Nussallee 12, 53115 Bonn, Germany
The hunt for spin-triplet superconductors has excited researchers for decades, with new candidates regularly being proposed as others are ruled out. This pairing of electrons into a Cooper pair state with total spin of one is allowed theoretically but has yet to be confirmed in a material. A system with these characteristics would have profound fundamental and technological implications. Here, we use ultra-low temperature scanning tunneling microscopy to measure the superconducting gap of UPt3, which reveals a zero-bias Andreev bound state in the surface perpendicular to the c-axis. The superconducting origin of the gap is confirmed via observation of a vortex lattice, as well as by suppression of the gap above the expected critical field and temperature. For triplet pairing, such an Andreev state is fragile against Rashba spin-splitting, whereas for singlet pairing it remains robust, strongly suggesting that UPt3 is a spin-singlet superconductor.
Keywords: UPt3; unconventional superconductivity; Andreev bound state; scanning tunneling microscopy