Observation of thickness dependent properties in novel multiferroic thin films

Multiferroics exhibit simultaneous coexistence of electric and magnetic ordering with coupling between two order parameters. These materials therefore find novel applications like multiple memories apart from MEMS sensors and actuators etc. Here we report the thickness dependent multiferroic properties of Bi_0.7Dy_0.3FeO₃ films grown on Pt/TiO₂/SiO₂/Si substrate by pulsed laser deposition technique. In these films, magnetic anisotropy is developed non-linearly with the thickness. It is correlated to stress developed during growth process due lattice mismatch, difference in thermal coefficient, internal defects etc. The lattice cell parameter c also changes arbitrarily with the thickness of the film but correlates with stress. The saturation polarization (P_s) values scale with c parameter. The information obtained by this study would be significantly useful in innovative devices planned with this advanced material.