Manifestation of helical edge states as zero bias magneto-tunneling-conductance peaks in noncentrosymmetric superconductors.

Helical edge states exist in the mixed spin singlet and triplet phase of a noncentrosymmetric superconductor (NCSS) when the pair amplitude (PA) in the negative helicity band, Δ(-), is smaller than the PA in the positive helicity band, Δ(+), i.e., when the PA in the triplet component is more than the same in the singlet component. We numerically determine energies of these edge states as a function of γ = Δ(-)/Δ(+). The presence of these edge states is reflected in the tunneling process from a normal metal to an NCSS across a bias energy eV. (i) Angle resolved spin conductance (SC) obeying the symmetry g(s)(φ) = -g(s)(-φ) shows peaks when the bias energy equals the available quasiparticle edge state energy provided [Formula: see text]. (ii) The total SC, G(s), is zero but modulates with eV for finite magnetic field H. (iii) The zero bias peaks of G(s) and total charge conductance, G(c), at finite H split into two at finite eV for moderate H. (iv) At zero bias, G(c) and G(s) increase with H and show peaks at |H|∼γH(0), where H(0) is a characteristic field.