Exchange bias in bismuth ferrite/cobalt ferrite Janus nanofibers

Abstract

Bismuth ferrite:cobalt ferrite (BiFeO₃:CoFe₂O₄) nanofibers with tailorable exchange bias effects were synthesized utilizing a Janus type morphology, wherein both phases are coupled longitudinally along the length of each fiber. By varying the relative phase amounts of BiFeO₃ and CoFe₂O₄ of the fibers, the interfacial area between the phases could be tuned and thereby the magnitude of exchange bias effects could also be tuned. Each BiFeO₃:CoFe₂O₄ wt% fiber system exhibited characteristic exchange bias effects, specifically increased anisotropy and coercivity. H_E, the magnitude of the shift in the center of the field cooled hysteresis loops, was found to have a direct relationship with interfacial area with a similar minimum for a 50 : 50 wt% sample and maximized as either phase weight percent was decreased.