Room temperature exchange bias in antiferromagnetic composite BiFeO3-TbMnO3

The magnetic property of a 0.7BiFeO(3)-0.3TbMnO(3) composite has been studied in detail and compared with that of 0.8BiFeO(3)-0.2TbMnO(3). The magnetic properties in 0.7BiFeO(3)-0.3TbMnO(3) are improved in manifold compared to BiFeO3. An exchange bias (H-EB) is observed in both the compositions of these antiferromagnetic composites, which varies between 5 and 180 Oe with a maximum at similar to 275 K. Isothermal remanent magnetization measurements at room temperature indicate the presence of an interfacial layer of a 2-dimensional dilute uniaxial antiferromagnet in a uniform magnetic field (2D DAFF). The presence of exchange bias can be explained on the basis of a strong strain-mediated magnetoelectric coupling induced exchange interaction and the creation of a 2D DAFF layer at the interface. The properties of this layer are defined by canting and pinning of BiFeO3 spins at the interface with TbMnO3 due to Fe and Mn interaction. X-ray magnetic circular dichroism confirms the presence of canted antiferromagnetic ordering of BiFeO3, charge transfer between Mn ions, and different magnetically coupled layers that play a vital role in the exchange bias.