Inhomogeneity-induced time-reversal symmetry breaking in cuprate twist junctions
Andrew C. Yuan, Yaar Vituri, Erez Berg, B. Spivak, Steven A. Kivelson
Abstract
The lowest-order Josephson coupling between $d$-wave superconductors vanishes by symmetry when the twist angle is close to 45 degrees. The authors propose here an ``order by disorder'' mechanism, whereby spatial fluctuations in the local Josephson coupling generate an effective higher-order coupling, leading to a time reversal symmetry breaking superconducting phase at the twisted interface. This mechanism may offer an explanation for recent experiments in twist junctions between high-${T}_{c}$ cuprate superconductors. These findings have broader implications for high-${T}_{c}$ cuprate physics, requiring a local admixture of an $s$-wave component in the $d$-wave order parameter.