Exchange coupled L10-FePt/fcc-FePt nanomagnets: Synthesis, characterization and magnetic properties

Abstract We report synthesis, characterization and magnetic properties of exchange-coupled L 1 0 -FePt/fcc-FePt nanomagnets. Structural and morphological characterization of exchange-coupled L 1 0 -FePt/fcc-FePt was carried out by powder X-ray diffraction, Mossbauer spectroscopy and transmission electron microscopy. Rietveld refinement of powder X-ray diffraction pattern has been used to quantify L 1 0 -FePt and fcc-FePt phases present in samples. Room temperature Mossbauer spectroscopy showed sextets of both L 1 0 -FePt and fcc-FePt phases with their respective hyperfine interaction parameters. Transmission electron microscopic (TEM and HRTEM) images confirmed nanocrystalline nature of exchange-coupled nanomagnets with particle size ranges from 15 nm to 50 nm after annealing for different time at 700 °C. Room temperature magnetic studies showed ferromagnetic nature of nanomagnets and maximum energy product (BH) max ~10.92 MGOe was obtained for sample containing 89.0% volume fraction of L 1 0 -FePt phase.