Spontaneous exchange bias in a nanocomposite of BiFeO3-Bi2Fe4O9

Abstract

We have observed a large as well as path-dependent spontaneous exchange bias (H-SEB) (similar to 30-60 mT) in a nanocomposite of BiFeO3-Bi2Fe4O9 across 5-300K when it is measured in an unmagnetized state following zero-field cooling and appropriate demagnetization. The path dependency yields a variation in the exchange bias depending on the sign of the starting field and the path followed in tracing the hysteresis loop. The asymmetry thus observed-Delta H-SEB-is found to be decreasing nonmonotonically across 5-300K with a peak around 200K. The Delta H-SEB together with large H-SEB could have significant ramification in tuning the exchange bias driven effects and consequent applications. (c) 2013 American Institute of Physics.