Exchange bias effect in Bi2Fe3AlO9 ceramics

Abstract

The exchange bias (EB) effect is observed in Bi2Fe3AlO9 polycrystalline ceramics. The EB field (HEB), vertical magnetization shift, and coercive field show a strong dependence on the cooling fields. When a larger applied field is used to measure the hysteresis loop, the EB effect is suppressed. The induced spin-glass-like phase via Al3+ doping is responsible for the EB effect below the spin-glass temperature (TSG) of ∼25 K. Moreover, the HEB varies nonmonotonically with temperature above TSG, which is interpreted using a random field model with the exchange coupling between ferromagnetic clusters and an antiferromagnetic phase.