1202.5898 (Tuhin Maity et al.)

Giant exchange bias in a nanocomposite of BiFeO3-Bi2Fe4O9    [PDF]

Tuhin Maity, Sudipta Goswami, Dipten Bhattacharya, Saibal Roy

We report our observation of an enormous spontaneous exchange bias (~40-60 mT) over a wide temperature range 5-300 K in a nanocomposite of BiFeO3 (~94%)-Bi2Fe4O9 (~6%). It originates from the exchange coupling interaction between frozen superspin glass moments in Bi2Fe4O9 (of average size ~19 nm) and antiferromagnetism in BiFeO3 (of average size ~112 nm) across the interfaces and its magnitude decreases with either increase or decrease in the volume fraction of Bi2Fe4O9. The spin structure at the interface exhibits an interesting rearrangement dynamics under a magnetic training operation. This large exchange bias can be exploited for yielding a colossal "exchange bias mediated multiferroic coupling" between ferroelectricity in BiFeO3 and magnetization in Bi2Fe4O9 within such a nanocomposite.

View original: http://arxiv.org/abs/1202.5898