Enhanced zero-bias conductance peak and splitting at mesoscopic interfaces between an $s$-wave superconductor and a 3D Dirac semimetal

TL;DR

This study demonstrates that conventional Nb superconductors induce unconventional superconducting features, including zero-bias conductance peaks and potential Majorana states, at interfaces with the topologically non-trivial Dirac semimetal Cd$_3$As$_2$, revealing new quantum phenomena.

Contribution

It shows that conventional superconductors can induce unconventional superconductivity and Majorana states at interfaces with 3D Dirac semimetals, expanding understanding of topological superconductivity.

Findings

Zero-bias conductance peaks observed at Nb/Cd$_3$As$_2$ interfaces.

Splitting of conductance peaks under certain conditions.

Evidence supporting the emergence of Majorana bound states.

Abstract

Mesoscopic point contacts between elemental metals and the topological 3D Dirac semimetal Cd$_3$As$_2$ have been recently shown to be superconducting with unconventional pairing while Cd$_3$As$_2$ itself does not superconduct. Here we show that the same superconducting phase at mesoscopic interfaces on Cd$_3$As$_2$ can be induced with a known conventional superconductor Nb where a pronounced zero-bias conductance peak is observed which undergoes splitting in energy under certain conditions. The observations are consistent with the theory of the emergence of Andreev bound states (ABS) due to the presence of a pair potential with broken time reversal symmetry. The data also indicate the possibility of Majorana bound states as expected at the interfaces between $s$-wave superconductors and topologically non-trivial materials with high degree of spin-orbit coupling.