Experimental evidence for exchange bias in polycrystalline BiFeO 3/Ni81Fe19 thin films

Abstract

We report on experimental evidence of exchange bias between a polycrystalline antiferromagnetic BiFeO3 and a ferromagnetic Ni 81Fe19 film at room temperature. The measured 17 Oe hysteresis loop shift corresponds to an exchange energy of 11 ×10 -3 erg/cm2 per unit area of the interface coupling the two films, which is comparable with those observed for similar epitaxially-grown systems. The azimuthal behavior of the longitudinal and transverse magnetization components revealed the presence of induced unidirectional and biquadratic anisotropies. A misalignment between unidirectional and biquadratic anisotropy axes was also observed. © 2011 American Institute of Physics.