Pressure Effects on Magnetically-Driven Electronic Nematic States in Iron-Pnictides

TL;DR

This paper investigates how external uniaxial strain influences the magnetic and nematic transitions in iron-pnictides using a classical SO(3) spin model, providing insights consistent with recent neutron scattering experiments.

Contribution

It introduces a simple classical model to analyze pressure effects on magnetic and nematic states in iron-pnictides, connecting theoretical predictions with experimental observations.

Findings

Magnetic transition temperature increases linearly with strain.

Nematic crossover becomes sharp only at very small strain.

Model aligns with recent neutron scattering data in BaFe2As2.

Abstract

In a magnetically driven electronic nematic state, an externally applied uniaxial strain rounds the nematic transition and increases the magnetic transition temperature. We study both effects in a simple classical model of the iron-pnictides expressed in terms of local SO(N) spins (with N = 3) which we solve to leading order in 1=N. The magnetic transition temperature is shown to increase linearly in response to an external strain while a sharp crossover, which is a remnant of the nematic transition, can only be identified for extremely small strain. We show that these results can reasonably account for recent neutron experimental data in BaFe2As2 by C. Dhital et al [1].