Growth of crystalline/amorphous biphase Sm–Fe–Ta–N magnetic nanodroplets

Thin films of biphase (amorphous/crystalline) magnetic Sm–Fe–Ta–N nanodroplets were fabricated at room temperature with 157 nm pulse laser deposition in nitrogen from a Sm13.8Fe82.2Ta4.0 target. The 50–100 nm biphase spherical nanodroplets consist of a 5–10 nm internal crystal portion surrounded by the external amorphous phase. Nitrogen fixation in the nanodroplets occurred in the plume. The films exhibit a ferromagnetic response of 2.5 kOe coercivity at room temperature. With further annealing and thermal treatment in nitrogen, the coercivity was increased to 5.0 kOe. The surrounding amorphous layer prevents post-ablation oxidization of the crystalline magnetic nucleus of the nanodroplet.