Tunneling transport in topological insulator normal metal/insulator/d-wave superconductor junctions

J Phys Condens Matter. 2012 Aug 15;24(32):325702, 1-6. doi: 10.1088/0953-8984/24/32/325702. Epub 2012 Jul 12.

Abstract

We investigate the tunneling conductance in a normal metal/insulator/d-wave superconductor (NM/I/d-wave SC) junction with a barrier of thickness d and with an arbitrary gate voltage V(0) applied across the barrier region, formed on the surface of a topological insulator, using the Dirac-Bogoliubov-de Gennes equation and Blonder-Tinkham-Klapwijk (BTK) formalism. We find that the tunneling conductance as a function of both d and V(0) displays an oscillatory behavior whose amplitude decreases with increase of V(0). We also find that when the Andreev resonant condition is met, the tunneling conductance approaches a maximum value of 2G(0), independent of the gate voltage V(0).