Particle-hole spectral asymmetry at the edge of multi-orbital noncentrosymmetric superconductors.

We demonstrate that in two-dimensional noncentrosymmetric superconductors with multi-orbital spin-triplet pairing the energy profile of the density of states at the edge can be asymmetric. We show that the structure of Andreev reflections generally leads to pairing states made of orbital configurations that are orbitally split due to low crystalline symmetry at the edge. The resulting pairing state has a mixed parity character in the orbital sector that, in the presence of reduced crystal symmetry at the edge, sets out an asymmetric profile for the spectral function. These findings indicate a path to design asymmetric spectral functions at the edge of superconductors with orbital degrees of freedom and time-reversal symmetry. The emerging signatures can be exploited for the detection of spin-triplet pairing equipped with internal degrees of freedom.