New nonmagnetic aliovalent dopants (Li+, Cu2+, In3+ and Ti4+): Optical and strong intrinsic room temperature ferromagnetism of perovskite BaSnO3

Abstract

Nonmagnetic Li+, Cu2+, In3+ and Ti4+ ions were employed to induce robust room temperature ferromagnetism in perovskite BaSnO3 for advanced spintronics applications. New BaSn0.96M0.04O3 (M = Li+, Cu2+, In3+ and Ti4+) compositions were synthesized by modified Pechini method. In all compositions, single phase of cubic BaSnO3 was detected in the XRD patterns without any impurities. The FTIR spectra displayed the distinctive vibrational absorption band of BaSnO3 and verified the absence of any impurities. The SEM images evidently showed a decrement of grain size alongside morphological changes for doped BaSnO3 compositions compared to the pure one. The band gap energy of BaSnO3 was considerably influenced by the incorporation of Li+, Cu2+, In3+ and Ti4+ dopants. BaSn0.96Cu0.04O3 sample exhibited the highest refractive index value and the minimum value was obtained for BaSn0.96Ti0.04O3. Remarkably, at equal concentration two of the used nonmagnetic elements showed the ability to induce room temperature ferromagnetism in BaSnO3 lattice. Herein, BaSn0.96Cu0.04O3 exhibits a robust and symmetrical ferromagnetic hysteresis loop with complete saturation magnetization (Ms) of 0.158 emu/g and coercivity (Hc) of 42 Oe. BaSn0.96Ti0.04O3 composition revealed a ferromagnetic behavior within magnetic field of± 5000 Oe and the trend was reversed for higher values to show a diamagnetic performance. The interaction between the 3d orbitals of Cu2+ (3d9) or Ti4+ (d0) with the trapped electrons in the oxygen vacancies encourage a ferromagnetic coupling in BaSnO3 structure. The outer shell orbitals of Cu2+ and Ti4+ dopants and the oxygen vacancies seem to play a significant role in the magnetic properties.