Magnetic Properties and Exchange Coupling Effects of Srfe12o19@Mfe2o4 (M=Co, Ni, Zn) as Hard-Soft Magnetic Ferrite Core-Shell Nanofibres

Abstract

In this study, SrFe 12 O 19 @MFe 2 O 4 (M=Co, Ni, Zn) core-shell nanofibers were fabricated by coaxial electrostatic spinning. The composites obtained at an annealing temperature of 900 °C are composed of SrFe 12 O 19 in pure phase and MFe 2 O 4 (M=Co, Ni, Zn) in different spinels. Sr@Ni and Sr@Zn, fibers all exhibit a unique core-shell structure, while Sr@Co fibers are connected by a lamellar structure. The single-phase hysteresis lines for each composite indicate the presence of exchange coupling effects between the hard/soft magnetic composite phases. The magnetic properties of the composites change as the soft magnetic material in the shell layer changes. Sr@Co has the highest Ms (69.43 emu/g) and Mr (33.82 emu/g), whereas Sr@Zn has the highest Hc (2927 Oe). The switching plant curves indicate that the best exchange coupling of the three groups of samples is for Sr@Co. The magnetic properties of the composites are explained in terms of the nanofibre diameter, the exchange coupling between the two phases and the nature of the soft magnetic phase itself. It is shown that the exchange coupling of composites is closely related to the type of composite.

Keywords: Ferrite nanofibres, Core-shell structure, Exchange coupling, SrFe12O19@MFe2O4