Highly crystalline core-shell FeCo-CoFe₂O₄ nanostructures

¹ Department of Physics, The Catholic University of America, Washington, DC 20064, USA
² The Vitreous State Laboratory, The Catholic University of America, Washington, DC 20064, USA

^a e-mail: philip@cua.edu

Received: 28 May 2013
Revised: 30 August 2013
Accepted: 3 September 2013
Published online: 27 September 2013

Abstract

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.