2025/06/26 by B. Ramachandran, Balakrishnan, Ramachandran
Engineering · Materials Science · #FOS: Physical sciences #Magneto-Optical Properties and Applications #Material Science and Thermodynamics #Materials Science (cond-mat.mtrl-sci) #Multiferroics and related materials #Strongly Correlated Electrons (cond-mat.str-el)
paper · pdf · doi:10.48550/arxiv.2506.21229
openalex publication_date 2025/06/26 · openalex created_date 2025/10/15 · openalex updated_date 2026/07/31
The probability density function (PDF) and cumulative density function (CDF) of bulk BiFeO3, nanostructured BiFeO3, and thick film of BiFeO2.85 were studied in detail based on their experimental absorption data. The goal of this study was to investigate the electronic transitions and the Urbach tail band in three samples of the magnetoelectric multiferroic BiFeO3. The PDF and CDF functions were derived from the absorption data of these substances in the UV-visible-NIR region of light spectrum. For the BiFeO3-based materials, charge transfer (p-d and/or p-p) transitions in the energy range of 2.5 eV to 5.5 eV were identified through PDF and CDF analysis. Furthermore, spin-orbit and electron-lattice interactions along with a low-symmetry crystal field cause two doubly degenerate d-d transitions of Fe3+ ions in the FeO6 octahedra of the BiFeO3 samples to occur between 1.5 eV and 2.5 eV. Additionally, the BiFeO3-based materials exhibited strong direct and weak indirect transitions near the band edge, which point to a complex band structure of BiFeO3. Finally, the energy of the defect-induced Urbach tail band was directly calculated by examining the CDF function of the materials, yielding estimated values of approximately 0.40 eV, 0.31 eV, and 0.33 eV for the bulk, nanostructured, and film BiFeO3 samples, respectively.