Perpendicular easy axis alignment of FePt nanoparticles on a platinum-(001) buffer layer for high-density magnetic recording

The phenomenon of atomic motion between the nanoparticle and its substrate was examined in constructing perpendicularly aligned FePt nanoparticle structures. Samples of iron-rich FePt nanoparticles synthesized by vapor phase or liquid phase synthesis techniques were deposited on a platinum-(001) buffer layer and annealed in a hydrogen atmosphere. Superconductive quantum interference device and x ray diffraction measurements for the in-plane and out-of-plane direction exhibited perpendicularly oriented magnetization and an L10 ordered phase with a perpendicular easy axis orientation. The coercivity was measured as approximately 4.3 kOe. In addition, high angle annular dark field-scanning transmission electron microscopy showed FePt alloy formation normal to the sample surface. The atomic distribution data showed iron diffusion into the platinum layer. These results might open a new path toward ultrahigh density storage media from chemically synthesized FePt nanoparticles.