Spontaneous exchange bias in a nanocomposite of BiFeO3-Bi 2Fe4O9

Abstract

We have observed a large as well as path-dependent spontaneous exchange bias (HSEB) (∼30-60 mT) in a nanocomposite of BiFeO 3-Bi2Fe4O9 across 5-300 K 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-ΔHSEB-is found to be decreasing nonmonotonically across 5-300 K with a peak around 200 K. The ΔHSEB together with large HSEB could have significant ramification in tuning the exchange bias driven effects and consequent applications. © 2013 American Institute of Physics.