High Resolution Polar Kerr Effect Measurements of Sr2RuO4: Evidence for Broken Time Reversal Symmetry in the Superconducting State

TL;DR

This study uses high-precision polar Kerr effect measurements to demonstrate broken time reversal symmetry in the superconducting state of Sr2RuO4, supporting its unconventional spin-triplet pairing nature.

Contribution

It provides direct experimental evidence of time reversal symmetry breaking in Sr2RuO4 using advanced Kerr effect measurement techniques.

Findings

Non-zero Kerr rotations observed below Tc

Evidence of broken time reversal symmetry

Large domain Kerr signals up to 65 nanorad

Abstract

Polar Kerr effect in the spin-triplet superconductor Sr2RuO4 was measured with high precision using a Sagnac interferometer with a zero-area Sagnac loop. We observed non-zero Kerr rotations as big as 65 nanorad appearing below Tc in large domains. Our results imply a broken time reversal symmetry state in the superconducting state of Sr2RuO4, similar to He3-A.