Surface influenced magnetostructural transition in FeRh films

Surface structural effects accompanying the antiferromagnetic-ferromagnetic magnetostructral transition of epitaxial FeRh thin films were investigated by grazing incidence x-ray scattering. Measurement of the film lattice parameters and variation of x-ray incident angles allow observation of the transition character on scales ranging from a few nm to the total through-thickness of the film. Out-of-plane lattice measurements confirm that the ferromagnetic phase nucleates from the surface during the heating process and is retained at the surface below the transition temperature during the cooling process. These results suggest that surface strain relief fosters nucleation of the ferromagnetic phase.