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.
Highlights
It was established already in the 1990s that a number of high-temperature superconductors have an order parameter with dx2−y2 symmetry [1]
We found a translational and time-reversal symmetry-breaking phase, in which a staggered pattern of fractional vortex-antivortex pairs forms like a necklace along the pairbreaking surface
The flux is generated by the fractional vortexantivortex phase, and the pair-breaking facet is formed by cutting away either a triangular corner or a triangular section in the middle of a square grain, as shown in Figs. 1 (a) and (b), respectively
Summary
It was established already in the 1990s that a number of high-temperature superconductors have an order parameter with dx2−y2 symmetry [1]. For an ideal specular surface with [110]-orientation, all scattering trajectories include the sign change, and the spectral weight of these zero-energy Andreev bound states is very large: they form a flat band at zero energy as function of momentum parallel to the interface, k. Shifting these mid-gap states to finite energies can lead to lowering of the free energy. Vorontsov found that a phase gradient can be generated through spontaneous time-reversal symmetry breaking in thin films [14, 26,27,28,29], caused by finite-size effects in the form of a proximity of two pair-breaking interfaces. This is done by considering a system with a single pair-breaking edge
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
