Andreev spectroscopy of nonhelical spin textures in topological insulators

Abstract

We study how nonhelical spin textures affect the proximity-induced superconductivity of topological insulator (TI)-superconductor (SC) interface states. In particular we calculate the conductance of lateral heterojunctions which comprise a TI surface that is only partially covered by a superconducting material. Interface potentials at the TI-SC interface may lead to a Fermi velocity and spin texture mismatch between the two regions of the lateral heterojunction. By enforcing the hermiticity of the total Hamiltonian, we derive the boundary conditions and calculate the conductance of the structure in both the normal and superconducting state. The total Andreev conductance is calculated for both $s$-wave and spin-triplet parent SCs, and for several examples of nonhelical spin textures which lead to different Fermi surface mismatches between the two planar regions of the heterojunction. We find that for spin-triplet SCs, nonzero conductance signatures only appear for certain combinations of nonhelical spin textures and parent superconducting material.

References in corpus (6)

• The electronic properties of graphene
• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• Chiral tunneling and the Klein paradox in graphene
• Andreev reflection and Klein tunneling in graphene
• Creation of spin-triplet Cooper pairs in the absence of magnetic ordering
• Mott scattering at the interface between a metal and a topological insulator

Cited by in corpus (3)

• Kekulé Induced Valley Birefringence and Skew Scattering in Graphene
• Bound states and controllable currents on Topological Insulator surfaces with extended magnetic defects
• Local density of state oscillations in laterally heterostructured topological insulator-semiconductor systems