Cu induced low temperature ordering of fct-FePtCu nanoparticles prepared by solution phase synthesis

Here, we report simple one-step solution phase synthesis for face-centered tetragonal FePtCu nanoparticles (NPs). Cu atoms are doped into the FePt lattice during synthesis, occupying Fe sites to form FePtCu alloy NPs. The phase and magnetic properties of the NPs can then be altered by varying the reaction conditions. We report room-temperature coercivities as high as 5.09 kOe for FePtCu NPs synthesized at 310 °C, significantly higher than the coercivity of pure FePt NPs without Cu doping. We suggest that Cu incorporation into the FePt lattice is responsible for the observed ordering enhancement of the as-prepared NPs, specifically increasing atomic diffusivity during the fcc-to-fct phase transformation. Our findings provide critical insights the effects Cu doping, namely its role in inducing atomic rearrangement and phase transformation of FePt NPs at low synthesis temperatures.