Highly crystalline core-shell FeCo-CoFe

Highly crystalline core-shell FeCo-CoFe2O4 nanowires were obtained from a three step process. Initially, CoFe2O4 nanowires were grown using electrospinning and annealing at higher temperatures. Through a thermal reduction under controlled conditions, CoFe2O4 nanostructures were converted to FeCo alloy nanowires. Then by natural oxidation, a highly crystalline shell of CoFe2O4 formed over the FeCo core structure. Structural and magnetic characterizations revealed the presence of highly crystalline FeCo-Co2FeO4 core-shell structure. Magnetically, the soft FeCo phase switches at a lower magnetic field compared to the hard CoFe2O4 phase, yielding an irregular hysteresis loop with a squeezed loop in the middle. The FeCo/CoFe2O4 core-shell is stable and it retains its structure for a prolonged duration