Fractional Vortices as Evidence of Time-Reversal Symmetry Breaking in High-Temperature Superconductors

Abstract

We argue that recent experiments by Kirtley et al. may show evidence of time-reversal symmetry breaking in ${\mathrm{YBa}}_2{\mathrm{Cu}}_3{O}_7$ at crystal grain boundaries. We illustrate this through a Ginzburg-Landau model calculation. Further experimental tests are proposed.