Magnetocaloric effect, electronic and magnetic properties of Ba1-xSrxFeO3 barium-strontium ferrites: Monte Carlo simulations and comparative study between TB-mBJ and GGA+U

Abstract

The magnetocaloric effect, electronic and magnetic properties of cubic perovskite oxide Ba1-xSrxFeO3 (BSFO) with x = 0 and 0.2 have been investigated using the method of linear augmented plane wave (FPLAPW) based on density functional theory (DFT) and Monte Carlo simulations. Spin polarization calculations has been studied using the full potential linearized augmented plane wave (FP-LAPW) method within generalized gradient approximation (GGA), Hubbard approximation (GGA + U), and modified Becke-Johnson potential (TB-mBJ). The total magnetic moment, Curie temperature, and exchange integrals were found to decrease with Sr substitution. The obtained results were in good agreement with the experimental ones. The spin polarization for Ba0.8Sr0.2FeO3 shows half-metallic ground state with the ferromagnetic coupling of Fe spin. The computed results are in good agreement with available theoretical results. The total magnetic moment and the exchange couplings are deduced from Ab initio calculations, using Monte Carlo simulations, to a quantitative agreement with the experimental transition temperatures. The magnetic entropy change decreased from 5.5 J.K−1. kg−1 to 4 J.K−1. kg−1 with substitution by Sr. This value of maximum magnetic entropy reaches the experimental value. Our results could show that BSFO has desirable magnetic properties that meet the needs of magnetic / spintronic devices.