Comprehensive study of Gd ₂ Ti ₂ O ₇ : Structural, electronic, magnetic, thermal, optical properties, and magnetocaloric effect

Abstract The Gd 2 Ti 2 O 7 compound has been thoroughly examined using first‐principles calculations within the density functional theory (DFT) framework, incorporating the Hubbard U correction, alongside Monte Carlo simulations. This study explores its structural, electronic, magnetic, mechanical, thermal, thermoelectric, optical, and thermodynamic properties, including its magnetocaloric effect. Structural analysis confirms the compound's stability in its antiferromagnetic configuration, with optimized lattice parameters showing excellent agreement with experimental data. Electronic band structure and density of states (TDOS and PDOS) analyses reveal that Gd 2 Ti 2 O 7 behaves as a semiconductor with a direct band gap of 3.5 eV. Elastic constant calculations and a negative formation energy indicate that the compound is mechanically and thermodynamically stable. Further mechanical analysis shows Gd 2 Ti 2 O 7 to be a ductile material with metallic bonding, as supported by Poisson's ratio and Pugh's ratio. To explore thermal behavior, transport properties such as the Seebeck coefficient (S), power factor ( PF ), thermal (κ e /τ) and electrical conductivities (σ e /τ), and the figure of merit ( ZT ) were determined, emphasizing its suitability for thermoelectric applications. Optical properties, including refractive index n (ω), reflectivity R (ω), extinction coefficient k (ω), dielectric constants ε (ω), optical conductivity σ (ω), energy loss L (ω), and absorption coefficient α (ω), were also examined, demonstrating suitability for optoelectronic devices. The quasi‐harmonic Debye model was employed to analyze the thermodynamic properties, confirming the compound's robustness across various temperature and pressure conditions. Moreover, the external magnetic field's effect on magnetic phase transitions, Néel temperature, and magnetization was analyzed. Calculations of magnetic entropy change and relative cooling capacity under different magnetic fields near the Néel temperature underscore the material's potential in magnetocaloric applications.