Transport signatures of a junction between a quantum spin Hall system and a chiral topological superconductor

E. G. Novik; B. Trauzettel; P. Recher

doi:10.1103/PhysRevB.101.235308

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Transport signatures of a junction between a quantum spin Hall system and a chiral topological superconductor

E. G. Novik, B. Trauzettel, P. Recher

DOI 10.1103/PhysRevB.101.235308 · Physical Review B

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Abstract

We investigate transport through a normal-superconductor (NS) junction made from a quantum spin Hall (QSH) system with helical edge states and a two-dimensional (2D) chiral topological superconductor (TSC) having a chiral Majorana edge mode. We employ a two-dimensional extended four-band model for HgTe-based quantum wells in a magnetic (Zeeman) field and subject to s-wave superconductivity. We show using the Bogoliubov-de Gennes scattering formalism that this structure provides a striking transport signal of a 2D TSC. As a function of the sample width (or Fermi energy) the conductance resonances go through a sequence of 2e2/h (nontrivial phase) and 4e2/h plateaux (trivial phase) which fall within the region of a nonzero Chern number (2D limit) as the sample width becomes large. These signatures are a manifestation of the topological nature of the QSH effect and the TSC.