Theory of surface Andreev bound states and tunneling spectroscopy in three-dimensional chiral superconductors

Abstract

We study the surface Andreev bound states (SABSs) and quasiparticle tunneling spectroscopy of three-dimensional (3D) chiral superconductors by changing their surface (interface) misorientation angles. We obtain an analytical formula for the SABS energy dispersion of a general pair potential, for which an original 4×4 BdG Hamiltonian can be reduced to two 2×2 blocks. The resulting SABS for 3D chiral superconductors with a pair potential given by kz(kx+iky)ν (ν=1,2) has a complicated energy dispersion owing to the coexistence of both point and line nodes. We focus on the tunneling spectroscopy of this pairing in the presence of an applied magnetic field, which induces a Doppler shift in the quasiparticle spectra. In contrast to the previously known Doppler effect in unconventional superconductors, a zero-bias conductance dip can change into a zero-bias conductance peak owing to an external magnetic field. We also study SABSs and tunneling spectroscopy for possible pairing symmetries of UPt3. For this purpose, we extend a standard formula for the tunneling conductance of unconventional superconductor junctions to treat spin-triplet nonunitary pairings. Magnetotunneling spectroscopy, i.e., tunneling spectroscopy in the presence of a magnetic field, can serve as a guide to determine the pairing symmetry of this material.

Source-reported materials — not catalogue approval

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