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Nodal superconductors without inversion symmetry have non-trivial topological properties, manifested by topologically protected flat-band edge states. Since the bulk is not fully gapped, the edge states of nodal superconductors can in principle be susceptible to impurities which break translational symmetry.
Using recursive Green's function techniques we study the robustness of the edge states against both magnetic and non-magnetic disorder. We show that for weak and dilute non-magnetic impurities, a finite number of midgap edge states remain at zero-energy. We compute the zero bias conductance of a junction between a normal lead and a non-centrosymmetric superconductor as a function of disorder strength. It is found that the flat-band edge states give rise to a nearly quantized zero-bias conductance, even in the presence of non-magnetic impurities. |
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