Collinear to Anti-collinear Quantum Phase Transition by Vacancies

TL;DR

This paper explores how vacancies induce a quantum phase transition from collinear to anti-collinear magnetic order in a frustrated Heisenberg model, revealing a new magnetic phase relevant to iron-based superconductors.

Contribution

It demonstrates that vacancies can rapidly suppress collinear order and induce a novel anti-collinear phase, providing insights into magnetic transitions without structural changes in superconductors.

Findings

Vacancies suppress collinear antiferromagnetic order.

A new anti-collinear magnetic phase is generated by vacancies.

The anti-collinear phase can exist independently of structural transitions.

Abstract

We study static vacancies in the collinear magnetic phase of a frustrated Heisenberg $J_1$-$J_2$ model. It is found that vacancies can rapidly suppress the collinear antiferromagnetic state (CAFM)and generate a new magnetic phase, an anti-collinear magnetic phase (A-CAFM), due to magnetic frustration. We investigate the quantum phase transition between these two states by studying a variety of vacancy superlattices. We argue that the anti-collinear magnetic phase can exist in iron-based superconductors in the absence of any preceding structural transitions and an observation of this novel phase will unambiguously resolve the relation between the magnetic and structural transitions in these materials.