Evaluation of Pressure Induced Physical and Magnetic Properties of A3CrO4(A=Mg, Ca, Sr) Alkali-Metal Oxides for Spintronics Applications Via DFT

Abstract

The present study employs density functional theory (DFT) within the CASTEP framework to systematically investigate the pressure-tunable structural, electronic and magnetic properties of A₃CrO₄ (A = Mg,Ca,Sr) alkali-metal oxides using GGA-PBE, GGA+U and GGA-PBEsol functionals. Structural optimization confirms that all A₃CrO₄ (A = Mg,Ca,Sr) compounds crystallize in the cubic P3m space group, with ferromagnetic (FM) ordering consistently more stable than non magnetic (NM) states across the entire pressure range of 0–30 GPa. Mg₃CrO₄ and Ca₃CrO₄ exhibit robust FM ground states with total magnetic moments of +4.0 to –4.1 μB maintaining half-metallicity under hydrostatic pressures up to 30 GPa. In contrast, Sr₃CrO₄ undergoes a pressure-induced magnetic phase transition, with its magnetic moment reversing sign at 20–30 GPa, indicating a shift toward antiferromagnetic (AFM) or ferrimagnetic ordering. Elastic constant analysis confirms dynamic stability across the entire pressure range (0–30 GPa). While Mg₃CrO₄ remains brittle under compression, Ca₃CrO₄ and Sr₃CrO₄ exhibit pressure induced ductility transitions, transforming from brittle to ductile behavior at higher pressures. Electronic structure calculations reveal persistent half-metallicity, with spin-down channels retaining wide band gaps and spin-up channels displaying metallic behavior. The application of Hubbard corrections (GGA+U) further validates the robustness of the electronic properties. The average sound velocity, Debye temperature, Debye frequency, melting temperature and Gruneisen parameter were analyzed under pressures up to 30 GPa. Mg₃CrO₄ and Ca₃CrO₄ show a steady increase in sound velocity, Debye temperature, and frequency, indicating lattice stiffening, stronger bonding and enhanced thermal stability. In contrast, Sr₃CrO₄ exhibits anomalous behavior, with values rising up to 20 GPa but slightly decreasing at 30 GPa, consistent with its pressure-induced magnetic reversal. Melting temperatures increase significantly for all compounds, confirming their suitability for high-temperature and high-pressure applications. The interplay between pressure and functional analyzing in these Cr-based compounds provides valuable insights for advancing spintronics and functional materials design.