Magnetic-Field-Induced Topological Reorganization of a P-wave Superconductor

TL;DR

This paper investigates how an applied magnetic field influences the spin structure and topological phases of a one-dimensional spin-triplet superconductor, revealing complex boundary effects and limitations of bulk-boundary correspondence.

Contribution

It provides a self-consistent analysis of the spin d-vector reorganization and its impact on topological phases and Majorana modes in a Zeeman field.

Findings

Magnetic field causes significant reorganization of the Cooper pair spin structure.

Boundary effects lead to spatial variation of the d-vector, affecting Majorana fermions.

Bulk-boundary correspondence can break down in interacting topological systems.

Abstract

In this work we illustrate the detrimental impact of the Cooper pair's spin-structure on the thermodynamic and topological properties of a spin-triplet superconductor in an applied Zeeman field. We particularly focus on the paradigmatic one-dimensional case (Kitaev chain) for which we self-consistently retrieve the energetically preferred Cooper pair spin-state in terms of the corresponding spin d-vector. The latter undergoes a substantial angular and amplitude reorganization upon the variation of the strength and the orientation of the field and results to a modification of the bulk topological phase diagram. Markedly, when addressing the open chain we find that the orientation of the d-vector varies spatially near the boundary, affecting in this manner the appearance of Majorana fermions at the edge or even altering the properties of the bulk region. Our analysis reveals the limitations and breakdown of the bulk-boundary correspondence in interacting topological systems.