Magnetic properties and exchange bias in BiFeO3/La2/3Sr1/ 3MnO3 heterostructure

A sizable exchange bias (HEB-30Oe at 10 K) in the magnetic hysteresis of BiFeO3/La2/3Sr1/3MnO3 heterostructure is observed under the cooling field (+/- 3 kOe) applied perpendicular to the surface of the films. The exchange bias field (HEB) decreases with increasing temperature and becomes zero above 200 K. The temperature-dependent field cooled (FC) and zero-field cooled (ZFC) magnetization curves show irreversible behaviour, with a blocking temperature (TB) -225 K. The coercive field of the hysteresis loop, below the blocking temperature, decays exponentially with increasing temperature. These magnetic characteristics of BiFeO3/La2/3Sr1/3MnO3 heterostructure point towards a possibility of a spin-glass-like state due to the magnetic exchange interactions between the magnetic ions of both the layers in the vicinity of the interface, leading to complex magnetic structure. The sizable exchange bias observed below the blocking temperature is most likely originated from the exchange coupling between the magnetic ions at the interface.