Magnetization in the Superconducting State of UPt$_3$ from Polarized Neutron Diffraction

TL;DR

This study uses polarized neutron diffraction to measure the bulk susceptibility of UPt$_3$, providing evidence for odd-parity, spin-triplet superconductivity by showing temperature-independent susceptibility across superconducting phases.

Contribution

First direct bulk measurement confirming the odd-parity, spin-triplet nature of UPt$_3$'s superconductivity using polarized neutron diffraction.

Findings

Temperature-independent susceptibility for H||a across superconducting phases

Supports odd-parity, spin-triplet pairing in UPt$_3$

Addresses conflicting previous experimental results

Abstract

The heavy fermion superconductor UPt$_3$ is thought to have odd-parity, a state for which the temperature dependence of the spin susceptibility is an important signature. In order to address conflicting reports from two different experiments, the NMR Knight shift and measurements of the anisotropy of the upper critical field, we have measured the bulk susceptibility in a high quality single crystal using polarized-neutron diffraction. A temperature independent susceptibility was observed for $H||a$ through the transitions between the normal state and the superconducting A-, B- and C-phases, consistent with odd-parity, spin-triplet superconductivity.