Evidence for the E_2u model of the superconducting order parameter in UPt_3 from Josephson interferometry

TL;DR

This study uses Josephson interferometry to provide phase-sensitive evidence supporting the E_2u model of the superconducting order parameter in UPt_3, indicating a complex order parameter with a Pi phase shift.

Contribution

The paper offers experimental phase-sensitive data that supports the E_2u model of the superconducting order parameter in UPt_3, advancing understanding of its pairing symmetry.

Findings

Asymmetric diffraction patterns indicate a complex order parameter.

Data shows a Pi phase shift consistent with the E_2u model.

Results support the unconventional superconductivity in UPt_3.

Abstract

We present data on the modulation of the critical current with applied magnetic field in UPt_3-Cu-Pb Josephson junctions and SQUIDs. The junctions were fabricated on polished surfaces of UPt_3 single crystals. The shape of the resulting diffraction patterns provides phase sensitive information on the superconducting order parameter. Our corner junction data show asymmetric patterns with respect to magnetic field, indicating a complex order parameter, and both our junction and SQUID measurements point to a phase shift of Pi, supporting the E_2u representation of the order parameter.