Alignment of chiral order parameter domains in Sr_{2} RuO_{4} by magnetic field cooling

TL;DR

This study demonstrates that magnetic field cooling can align chiral domains in Sr$_{2}$RuO$_{4}$, significantly enhancing Josephson junction critical currents and providing evidence of domain control in unconventional superconductors.

Contribution

It provides experimental evidence that magnetic field cooling can align chiral domains in Sr$_{2}$RuO$_{4}$, affecting Josephson junction behavior.

Findings

Magnetic field cooling enhances critical current in Sr$_{2}$RuO$_{4}$/Cu/Pb junctions.

Chiral domains in Sr$_{2}$RuO$_{4}$ can be aligned by magnetic fields.

Alignment of domains modifies phase interference effects in Josephson junctions.

Abstract

Superconductivity in Sr$_{2}$RuO$_{4}$ is unconventional, believed to be of $p_{x}\pm ip_{y}$ pairing symmetry. These two degenerate order parameters allow the formation of chiral domains separated by domain walls. In a Josephson junction formed on the edge of a single crystal of Sr$_{2}$RuO$_{4}$, the chiral domains can create a variation of the phase in the tunneling direction causing interference effects which suppress and modulate the critical current of the junction. Cooling the junction in a magnetic field lifts the degeneracy between the order parameter states and induces a preferential chirality, significantly modifying the phase interference. We present experimental results on Sr$_{2}$RuO$_{4}$/Cu/Pb Josephson junctions cooled in a magnetic field showing a dramatic enhancement of their critical current, giving direct evidence for the presence of chiral domains and their alignment in a magnetic field.