Electrical and Thermal conductance through a Nodal Surface Semimetal-Insulator-Superconductor junction

Abstract

Motivated by the unique dispersions close to the two dimensional band crossing in a topologically charged nodal surface semimetal (NSSM) spectrum, we perform theoretical analysis of quantum tunnelling through a junction consisting of such NSSM, an insulator and a s-wave superconductor (acronymed NSSM-I-SC junction). In particular, for excitation energies both more and less than the superconducting gap potential $\Delta$ we probe the normal and Andreev conductance for different incident orientations and thereby find the tunnelling electrical conductance through the heterostructure. The present work considers only the thin barrier limit which witness the conductance G to oscillate periodically with frequency $\pi$ as a function of the barrier strength, both in high and low doping limit. Such periodic behavior is also observed while calculating the thermal conductance $\kappa$ through the junction. Novelty of this problem is that the behavior of these G or $\kappa$ with insulator width are, in many respect, different compared to that from a normal metal - insulator - superconductor (NIS) junction on graphene or silicene. The findings can thus motivate experimentalists to culture renewed control over electric or thermal transport on topological materials.