General framework for transport in spin-orbit-coupled superconducting heterostructures: Nonuniform spin-orbit coupling and spin-orbit-active interfaces

TL;DR

This paper develops a comprehensive theoretical framework for understanding transport phenomena in one-dimensional superconducting heterostructures with nonuniform spin-orbit coupling and spin-active interfaces, crucial for topological and spintronic research.

Contribution

It introduces a generalized model extending the Blonder-Tinkham-Klapwijk approach to account for nonuniform SOC and interfacial effects in superconducting heterostructures.

Findings

Reveals diverse transport behaviors influenced by SOC variations.

Provides insights into topological states and Majorana fermions.

Establishes a basis for experimental characterization of SOC effects.

Abstract

Electronic spin-orbit coupling (SOC) is essential for various newly discovered phenomena in condensed-matter systems. In particular, one-dimensional topological heterostructures with SOC have been widely investigated in both theory and experiment for their distinct transport signatures indicating the presence of emergent Majorana fermions. However, a general framework for the SOC-affected transport in superconducting heterostructures, especially with the consideration of interfacial effects, has not been developed even regardless of the topological aspects. We hereby provide one for an effectively one-dimensional superconductor-normal heterostructure with nonuniform magnitude and direction of both Rashba and Dresselhaus SOC as well as a spin-orbit-active interface. We extend the Blonder-Tinkham-Klapwijk treatment to analyze the current-voltage relation and obtain a rich range of transport behaviors. Our work provides a basis for characterizing fundamental physics arising from spin-orbit interactions in heterostructures and its implications for topological systems, spintronic applications, and a whole variety of experimental setups.