Exploring room-temperature ferromagnetism and half-metallicity in new halide perovskites RbCrX3(X: F, Cl, Br, I) using first-principles and Monte Carlo simulations

A new class of halide perovskite RbCrX3(X = F, Cl, Br, I) compounds with a cubic crystal structure was examined using first-principles calculations. The proposed perovskite compounds exhibit promising stabilities in the cubic crystal structure, such as structural stability evidenced by the negative formation energy, phonon spectrum confirmed dynamic stability, and the Born-Huang stability criteria indicating mechanical stability. The computed electronic characteristics reveal the half-metallic nature of all these investigated compounds under ambient conditions, which is robust up to +/- 3% volumetric strain. The GGA+SOC total energy calculation yields that the single-ion anisotropy is very small in all these compounds, and thez-axis is a hard axis in all these compounds. Based on the total energy, the difference in total energy is 0.007 meV with reference to the hard axis. Ultimately, we further studied FM, AFM1, and AFM2 interactions by considering 2x2x2 supercell of a halide perovskite RbCrX3compounds.To estimate transition temperature (T-c), we used the mean field theory (MFT) and quantum Monte Carlo (MC) simulations. The estimated Curie temperature using QMC is 465.3 K, 536.7 K, 668.2 K, and 643.5 K with +/- 4.5% error for RbCrF3, RbCrCl3, RbCrBr3, and RbCrI3 compounds, respectively. Our finding provides fresh recommendations and predicts that halide perovskite RbCrX3 compounds are new candidate materials for room-temperature spintronic nanodevices application. For the first time, we are presenting the results for halide perovskite compounds based on rubidium and chromium atoms.