Strain-Tunable Mechanical, Electronic and Optical Properties of La₂AlGaO₆ Hybrid Perovskite: A First-Principles Investigation

Abstract

Perovskite materials, well-known for their structural flexibility and multifunctional characteristics, continue to attract attention for advanced electronic and optoelectronic applications. In this work, the elastic and strain-engineered electronic, mechanical, and optical properties of orthorhombic La₂AlGaO₆ (LAGO)-a hybrid perovskite formed by combining LaAlO₃ and LaGaO₃-are systematically investigated using first-principles density functional theory (DFT) calculations. Structural optimizations were performed using both the local density approximation (LDA) and the generalized gradient approximation (GGA). Mechanical stability was verified through the Born-Huang criteria, and the computed elastic constants (C₁₁, C₁₂, C₃₃, C₄₄, and C₆₆) were employed to derive key mechanical parameters, including Young's modulus, bulk modulus, shear modulus, Poisson's ratio, Cauchy's pressure, and anisotropy factor, providing insights into the material's ductility, hardness, and elastic anisotropy. Furthermore, the influence of biaxial strain on the electronic band structure, total and partial density of states (DOS/PDOS), and Fermi energy was analyzed, revealing pronounced band gap modulation under both compressive and tensile strains, accompanied by significant changes in optical behavior. The strong coupling between elastic response and electronic structure underscores LAGO's potential for tunable device applications, where mechanical stimuli can effectively tailor its electronic and optical functionalities.