Effects of (Sm, Mn and Ni) co-doping on structural, optical and magnetic properties of BiFeO3 thin films fabricated by a sol-gel technique

• (Sm, Mn and Ni) co-doped BFO films were prepared on quartz substrates by sol-gel.
• Ions co-doping plays a key role to modify optical and magnetic properties of BFO.
• The BSFMN film has potential applications in storage and optoelectronic devices.

Bi0.9Sm0.1FeO3 (BSF), Bi0.9Sm0.1Fe0.95Mn0.05O3 (BSFM) and Bi0.9Sm0.1Fe0.9Mn0.05Ni0.05O3 (BSFMN) thin films were grown on the quartz substrates by a sol-gel technique, respectively. Structural characterizations and microstructural analysis show that all the films exhibit polycrystalline perovskite structures with dense and smooth microstructures. The most intense diffraction peak (110) shifts toward lower diffraction angles, which is associated with lattice strain estimated by Williamson-Hall analysis model. Moreover, optical absorption spectra indicate that the co-doping of Sm, Mn and Ni has an effect on the energy band structure. The band gap of the films decreases from 2.61 eV (BSF) to 2.46 eV (BSFMN). Furthermore, the BSFMN film exhibits a maximum saturated magnetization compared with BSF and BSFM films, which mainly stems from the local ferromagnetic spin configuration.