Metamagnetic transition in size-selected FeRh B2 nanocrystals

Near equiatomic composition, FeRh bulk alloys exhibit a CsCl-type (B2) chemically ordered phase related to a metamagnetic transition from an antiferromagnetic (AFM) to a ferromagnetic (FM) state close to ambient. This first order metamagnetic transition is generally interpreted in terms of the collapse of induced Rh magnetic moment at low temperature. The objective of this proposal is to study thermally driven chemical order transition and magnetism in bi-metallic FeRh nanoalloys. To reach this purpose, X-ray absorption spectroscopy and magnetic circular dichroism (XAS/XMCD) experiments on ID12 will be performed at both Fe K-edges and Rh L-edges on in-situ UHV annealed mass-selected FeRh nanoparticles (NPs) embedded in amorphous carbon matrix. These results will allow us to describe local structural and magnetic evolution for each specific element as a function of FeRh clusters size.