Role of A Cation Vacancy in the Exchange-Biased LaFeO3 Multiferroic Nanocrystals

Abstract

Multiferroic samples with the chemical formula La $_{1-x}\square _{x}$ FeO3 (0.0 ≤ x ≤ 0.03) were successfully prepared in nanoscale by citrate nitrate combustion method. XRD data reveals crystallized single-phase orthorhombic symmetry for the prepared nanopowder. All measured magnetic parameters point to the antiferromagnetic character with weak ferromagnetic moment. The value of the molar magnetic susceptibility (χ M ) for La $_{\mathrm {0.99}}\square _{\mathrm {0.01}}$ FeO3 reaches 3.5 times that of the undoped sample. The saturation magnetization of the samples La $_{\mathrm {0.99}}\square _{\mathrm {0.01}}$ FeO3 and La $_{\mathrm {0.97}}\square _{\mathrm {0.03}}$ FeO3 increased two times as compared with that of the parent one. The exchange bias (EB) effect was observed for 1st time at room temperature and originated from antiferromagnetic–ferromagnetic (AFM-FM) interface effect. Ferroelectric hysteresis loop was observed at room temperature for the samples which highlighted the presence of the ferroelectric ordering. A huge enhancement in the saturation (P s), the remnant polarization (P r), and the coercive electric field (E c) of the sample La $_{\mathrm {0.98}}\square _{\mathrm {0.02}}$ FeO3 by 7.5, 24, and 12 times, respectively, when compared with the parent sample LaFeO3. Based on the obtained results, the investigated samples are categorized in type I multiferroics.