Effects of magnetoelastic coupling: critical behavior and structure deformation

Abstract We study a 3D crystal where each atom interacts with neighbors via elastic and magnetic interactions by Monte Carlo simulation. The distance dependence of both interactions is supposed to be the Lennard–Jones potential and the spins are of the Ising type. When the magnetic interaction strength is much smaller than the elastic one, the magnetic transition remains in the 3D Ising criticality. With larger magnetic interaction, the critical exponents get very close to those of the 3D XY universality and not far from Fisher renormalized Ising exponents. For strong magnetic interaction, we show that as the temperature increases the crystal is broken into ferromagnetic domains separated by domain walls consisting of contracted antiferromagnetic spin pairs.