Manifestation of helical edge states as zero-bias magneto-tunneling-conductance peaks in non-centrosymmetric superconductors

Abstract

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, ${\Delta }_{-}$, is smaller than the PA in the positive helicity band, ${\Delta }_{+}$, 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 $\gamma ={\Delta }_{-}/{\Delta }_{+}$. 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 $g_s(\varphi )=-g_s(-\varphi )$ shows peaks when the bias energy equals the available quasiparticle edge state energy provided $|eV|\lesssim {\Delta }_{-}$. (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 $|H|\sim \gamma H_0$ where $H_0$ is a characteristic field.

minor changes; one figure is added

References in corpus (7)

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• Quantum Spin Hall Insulator State in HgTe Quantum Wells
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Cited by in corpus (3)

• Observation of Andreev bound state and multiple energy gaps in the non-centrosymmetric superconductor BiPd
• Nature and symmetry of the order parameter of the noncentrosymmetric superconductor Li2Pt3B
• Effect of helical edge states on the tunneling conductance in ferromagnet/noncentrosymmetric superconductors junctions