Effects of defects in the XY chain with frustrated boundary conditions

TL;DR

This paper investigates how different types of defects affect the novel bulk orders in the frustrated XY chain, revealing that certain defects can restore or stabilize these unconventional orders, thus supporting their potential experimental detection.

Contribution

It demonstrates the robustness of frustrated boundary condition-induced orders against specific defects, highlighting their stability and experimental relevance.

Findings

Ferromagnetic defects restore traditional antiferromagnetic order.

Antiferromagnetic defects stabilize incommensurate order.

Frustrated order remains robust against certain defect types.

Abstract

It has been recently proven that new types of bulk, local order can ensue due to frustrated boundary condition, that is, periodic boundary conditions with an odd number of lattice sites and anti-ferromagnetic interactions. For the quantum XY chain in zero external fields, the usual antiferromagnetic order has been found to be replaced either by a mesoscopic ferromagnet or by an incommensurate AFM order. In this work we examine the resilience of these new types of orders against a defect that breaks the translational symmetry of the model. We find that, while a ferromagnetic defect restores the traditional, staggered order, an AFM one stabilizes the incommensurate order. The robustness of the frustrated order to certain kinds of defects paves the way for its experimental observability.