Surface modification and enhanced multiferroic behavior of BiFe_0.25Cr_0.75O₃ films with different thickness over Pt(111)/Ti/SiO₂/Si substrate

Polycrystalline BiFe_0.25Cr_0.75O₃ thin films have been fabricated via a chemical deposition technique at various thicknesses (60-, 130-, 190-, 240 nm). The effect of Cr substitution on BiFeO₃ structures have been briefly discussed by performing X-ray diffraction and SAED pattern. The nature of the films surface at different thicknesses were briefly discussed using scanning electron microscope and transmission electron microscope. Roughness and other amplitude parameters of the film at different thickness are studied through atomic force microscopy. The result indicates that, when changing the thickness of the film, the average bond length gets changed causing difference in electrical and magnetic properties. Electrical and dielectric study reveals thickness dependent property and is deeply understood from space charge, oxygen vacancies and super-exchange interaction. Film at 60 nm shows higher magnetization with 8.5042 emu/cm³ and with a retentivity of 3.852 emu/cm³ than the thick film. Further, the spin-cooling behavior and magnetization below room temperature from 2 to 300 K were analyzed briefly for spintronics applications.