Absence of zero field muon spin relaxation induced by superconductivity in the B phase of UPt$_3$

TL;DR

This study uses muon spin relaxation measurements to investigate the magnetic properties of UPt$_3$'s B phase, finding no evidence of spontaneous magnetic fields associated with superconductivity, contrary to previous reports.

Contribution

The paper provides new experimental evidence showing the absence of zero-field muon spin relaxation signals in UPt$_3$'s B phase, challenging earlier findings.

Findings

No increase in internal magnetic field in the B phase

Sets an upper bound on possible magnetic fields in the superconducting state

Contradicts previous reports of magnetic field emergence in the B phase

Abstract

We present muon spin relaxation measurements performed on crystals of the heavy fermion superconductor UPt$_3$. In zero applied field, contrary to a previous report, we do not observe an increase of the internal magnetic field in the lower superconducting phase (the B phase). Our result gives an experimental upper bound of the magnetic field that could be associated with the superconducting state.