Phase Separation in Kitaev Chain

TL;DR

This paper investigates how including multiple order parameters in the Kitaev chain model affects its phase behavior, revealing that the superconducting state becomes susceptible to phase separation under certain interactions.

Contribution

It introduces a comprehensive analysis of the Kitaev chain considering multiple order parameters, showing the emergence of phase separation not seen in simpler models.

Findings

Superconducting state prone to phase separation with moderate to strong attraction.

Inclusion of additional order parameters significantly alters the phase diagram.

Phase separation occurs under conditions previously thought stable.

Abstract

Kitaev chain is a one-dimensional spinless fermion model that has $p$-wave superconducting (SC) states and Majorana zero modes at the edge. Usually this model is analyzed by taking only SC order parameter (OP) into account, but the situation significantly changes when OPs other than the SCOP are included. It turns out that the SC state in the latter case is prone to phase separation for moderate to strong attractiive interactions.