Effect of annealing process on dielectric and multiferroic properties of Sol-Gel derived bismuth chromate thin films

ABSTRACT Multiferroic materials such as BiCrO3, uniquely exhibit ferroelectricity and ferromagnetism simultaneously have been extensively studied for spintronics device applications. Conversely, the origin of multiferroicity remains poorly understood. In this paper, the structural phases of BiCrO3 over Pt (111)/Ti/SiO2/Si substrate and their lattice distortions after careful annealing were carefully investigated to explain their multiferroicity. Structural transition and different phases was studied from X-ray diffraction at different annealing temperature from 400°C to 700°C and the size of the grains were calculated from Scherrer's equation. SEM and AFM reveal nano-rod formation and the size and density of nano-rods tends to increase with increase of temperature. The step height variation and surface outgrowth of the films at different annealing temperature were further studied by measuring root mean square (RMS) and roughness (Rq) values. The frequency dependent dielectric behavior with terrific dielectric constant and dielectric loss were observed using LCRQ meter. Structural transformation also results an improved (well saturated) ferromagnetism at 700°C from weak ferromagnetism at 400°C due to addition of extra phases. This kind of approach could be used to probe the origin of multiferroic properties in rare-earth materials for device applications.