Intrinsic Room-Temperature Ferromagnetism in New Halide Perovskite AgCrX (X: F, Cl, Br, I) Using Ab Initio and Monte Carlo Simulations.

Herein, we present a detailed comparative study of the structural, elastic, electronic, and magnetic properties of a series of new halide perovskite AgCrX (X: F, Cl, Br, I) crystal structures using density functional theory, mean-field theory (MFT), and quantum Monte Carlo (MC) simulations. As demonstrated by the negative formation energy and Born-Huang stability criteria, the suggested perovskite compounds show potential stability in the cubic crystal structure. The materials are ductile because the Pugh's ratio is greater than 1.75, and the Cauchy pressure (C-C) is positive. The ground state magnetic moments of the compound were calculated as 3.70, 3.91, 3.92, and 3.91 μ for AgCrF, AgCrCl, AgCrBr, and AgCrI, respectively. The GGA + SOC computed spin-polarized electronic structures reveal ferromagnetism and confirm the metallic character in all of these compounds under consideration. These characteristics are robust under a ±3% strained lattice constant. Using relativistic pseudopotentials, the total energy is calculated, which yields that the single ion anisotropy is 0.004 meV and the -axis is the hard-axis in the series of AgCrX (X: F, Cl, Br, and I) compounds. Further, to explore room-temperature intrinsic ferromagnetism, we considered ferromagnetic and antiferromagnetic interactions of the magnetic ions in the compounds by considering a supercell with 2 × 2 × 2 dimensions. The transition temperature is estimated by two models, namely, MFT and MC simulations. The calculated Curie temperatures using MC simulations are 518.35, 624.30, 517.94, and 497.28 K, with ±5% error for AgCrF, AgCrCl, AgCrBr, and AgCrI compounds, respectively. Our results suggest that halide perovskite AgCrX compounds are promising materials for spintronic nanodevices at room temperature and provide new recommendations. For the first time, we report results for novel halide perovskite compounds based on Ag and Cr atoms.