Effect of holmium (Ho) and (Ho, Mn) co-substitution on the magnetic and magnetoelectric properties of bismuth ferrites

Bismuth Ferrites (BFO) doped and co-doped with Holmium (Ho) and Manganese (Mn) have gathered attention for their multiferroic and magnetoelectric properties at ambient temperature, positioning them as promising candidates for applications in spintronics, optoelectronics, and memory storage devices. This study investigates the magnetic and magnetoelectric characteristics of both pristine BiFeO${}_3$ and its variants doped with Ho and co-doped with (Ho, Mn). The work provides insights into recent advances in understanding the mechanisms influencing band gaps and magnetoelectric coupling in (Ho, Mn) co-doped BFO, with a particular focus on the role of dopants in modulating its multiferroic behaviour. Structural and morphological properties were examined using X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM), while X-ray Photoelectron Spectroscopy (XPS) enabled an analysis of the energy bands and molecular structure. Diffuse reflectance spectroscopy reveals a progressive decrease in the band gap with increasing Mn substitution at the iron sites, enhancing the material’s potential for optoelectronic applications. Magnetic hysteresis (M-H) and temperature-dependent magnetization (M-T) studies demonstrate enhanced ferromagnetic properties with Ho doping, while antiferromagnetic ordering is observed in samples co-doped with Mn, especially at lower temperatures. Holmium doping is shown to increase magnetoelectric coupling relative to pure BFO, though the coupling strength diminishes with higher Mn levels. These findings suggest that tailored (Ho, Mn) doping can significantly influence the magnetoelectric and optical properties of BFO, offering pathways for optimizing BFO in advanced multifunctional applications.