Exploring structural dependence of magnetic properties in FePt nanoparticle by Cs-corrected HRTEM

Well-separated and size-controlled FePt nanoparticles are promising for magnetic data storages with ultra-high areal densities [1]. Chemically ordered L1o-FePt shows high magneto-crystalline anisotropy and an enhanced coercivity as compared to disordered FePt state. A measurement of coercivity (Hc) of FePt, showing strongly size dependence (shown in another paper), indicates a lower anisotropy when nanoparticle is small, which could be structural dependence. Newly-developed TEM techniques, Cscorrector and exit wave reconstruction, supplying less delocalized image, has enabled us to directly explore the structure of nanoparticle even with lateral dimension of only a few atoms[2]. In this work, an objective-lens Cs-corrected Titan FEI 80-300 microscope was used to explore the intrinsic structural characteristic of FePt particle with different sizes, and try to establish the structure-property relationship.