Dislocation Majorana zero modes in perovskite oxide 2DEG

TL;DR

This paper proposes that dislocations in 2D superconducting oxide interfaces can host Majorana zero modes, offering a potentially cleaner experimental signature compared to traditional boundary-based detection methods.

Contribution

It introduces a new mechanism for realizing Majorana zero modes at crystalline dislocations in 2D oxide superconductors with weak topological indices, using anisotropic orbital dispersion.

Findings

Dislocations can host isolated Majorana zero modes without additional low-energy states.

Weak topological superconductivity can be achieved in SrTiO3 and KTaO3 2DEGs.

Potential for experimental detection of Majorana modes at dislocations.

Abstract

Much of the current experimental efforts for detecting Majorana zero modes have been centered on probing the boundary of quantum wires with strong spin-orbit coupling. The same type of Majorana zero mode can also be realized at crystalline dislocations in 2D superconductors with the nontrivial weak topological indices. Unlike at an Abrikosov vortex, at such a dislocation, there are no other low-lying midgap states than the Majorana zero mode so that it avoids usual complications encountered in experimental detections such as scanning tunneling microscope (STM) measurements. We will show that, using the anisotropic dispersion of the $t_{2g}$ orbitals of Ti or Ta atoms, such a weak topological superconductivity can be realized when the surface 2DEG of SrTiO$_3$ or KTaO$_3$ becomes superconducting, which can occur through either intrinsic pairing or proximity to existing s-wave superconductors.