From LaAlO3 insulator to multifunctional perovskite: DFT insights into europium-enhanced spin, optical, and elastic properties

Abstract

This study employs first-principles calculations to systematically investigate the structural, elastic, electronic, magnetic, optical, and thermodynamic properties of Eu_xLa_1−xAlO₃ perovskites (x = 0–1) for advanced spintronic and optoelectronic applications. Using density functional theory (DFT) within the Full-Potential Linearized Augmented Plane Wave (FP-LAPW) framework, we incorporate the around-mean-field (AMF) correction scheme method to address strong electron correlations in Eu f states and the modified Becke–Johnson (mBJ) potential to refine electronic and magnetic predictions. Structural analysis reveals a symmetry transition from cubic (Pm3m) in LaAlO₃ and EuAlO₃ to tetragonal (P43m) at intermediate compositions, with a peak bulk modulus (516.4 GPa) at x = 0.5, indicating enhanced mechanical strength. Magnetic moments scale linearly with Eu content, reaching 48 μ_B per 40-atom supercell in EuAlO₃, driven by localized Eu 4f electrons. Electronic structure calculations show a transition from a wide-band-gap insulator (4.34 eV in LaAlO₃) to half-metallic behavior at x ≥ 0.25, with full spin polarization at the Fermi level. Optical properties exhibit a redshift in absorption edges and increased anisotropy with Eu doping, while the static refractive index rises from ~ 1.7 (x = 0) to ~ 7.0 (x = 1). Thermodynamic stability is confirmed by negative formation energies, with EuAlO₃ being the most stable. These findings highlight the tunability of Eu_xLa_1−xAlO₃ perovskites, making them promising candidates for applications in spintronics, optoelectronics, and thermomechanics. Future work should focus on experimental validation and device integration.