Polarized Neutron Reflectometry of Epitaxial Fe[0.25 + x] Pt[0.75 – x] Layers

Epitaxial Fe $[ 0.25 +\mathrm {x}]$ Pt[0.75 – x] layers can be either antiferromagnetic (AF) or ferromagnetic (FM) depending on the degree of chemical ordering controlled by the deposition temperature. Our neutron diffraction studies were the first to study AF phase transitions in these thin films [1] and we have also shown using PNR that a mixed AF-FM film is exchange biased with itself [2]. In AF-FM exchange-biased superlattices with a modulated chemical order parameter, PNR shows the magnetization can be modulated through the film thickness with no composition modulations [3]. Our recent results reveal that He
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ion bombardment and annealing can be applied toward controlling magnetic phases in epitaxial Fe[0.25]Pt[0.75] layers [4].