Title: Spontaneous generation of fractional vortex-antivortex pairs at single edges of high-Tc superconductors,
Abstract: Unconventional d-wave superconductors with pair-breaking edges are predicted
to have ground states with spontaneously broken time-reversal and translational
symmetries. We use the quasiclassical theory of superconductivity to
demonstrate that such phases can exist at any single pair-breaking facet. This
implies that a greater variety of systems, not necessarily mesoscopic in size,
should be unstable to such symmetry breaking. The density of states averaged
over the facet displays a broad peak centered at zero energy, which is
consistent with experimental findings of a broad zero-bias conductance peak
with a temperature-independent width at low temperatures.