Peierls-like transition induced by frustration in a two-dimensional antiferromagnet

TL;DR

Introducing frustration into a 2D antiferromagnetic model induces a Peierls-like transition to an orthorhombic phase, with implications for real materials like Li2VOSiO4.

Contribution

This study demonstrates that frustration can cause a Peierls-like transition in a 2D antiferromagnet, revealing a new mechanism for structural phase changes.

Findings

Frustration induces a transition from tetragonal to orthorhombic phase.

The orthorhombic states are characterized by an Ising order parameter.

Implications discussed for Li2VOSiO4 as a real-world example.

Abstract

We show that the introduction of frustration into the spin-1/2 two-dimensional (2D) antiferromagnetic Heisenberg model on a square lattice via a next-nearest neighbor exchange interaction can lead to a Peierls-like transition, from a tetragonal to an orthorhombic phase, when the spins are coupled to adiabatic phonons. The two different orthorhombic ground states define an Ising order parameter, which is expected to lead to a finite temperature transition. Implications for ${\rm Li_2VOSiO_4}$, the first realization of that model, will be discussed.