Strong short-range magnetic order in a frustrated FCC lattice and its possible role in the iron structural transformation

TL;DR

This study explores how strong short-range magnetic order in a frustrated FCC lattice may influence the structural phase transition in iron, revealing significant magnetic correlations above the Neel temperature.

Contribution

It provides a theoretical analysis of magnetic properties in a frustrated FCC Heisenberg antiferromagnet, linking magnetic order to iron's structural transformation.

Findings

Strong short-range magnetic order exists above T_N in frustrated FCC lattices.

The Neel temperature depends on the ratio J2/J1.

Application to iron suggests magnetic order may influence structural phase transitions.

Abstract

We investigate magnetic properties of a frustrated Heisenberg antiferromagnet with a face-centered cubic (FCC) lattice and exchange interactions between the nearest- and next-nearest neighbours, J1 and J2. In a collinear phase with the wave vector Q = (pi,pi,pi) the equations of the self-consistent spin-wave theory for the sublattice magnetization and the average short range order parameter are obtained and numerically solved. The dependence of the Neel temperature T_N on the ratio J2/J1 is obtained. It is shown, that at strong enough frustration there is a wide temperature region above T_N with strong short range magnetic order. Application of this result to description of structural phase transition between alpha and gamma-phase of Fe is considered.