A DFT + U scheme combined with Monte Carlo simulation to model the magnetocaloric effect and physical properties of the MnCoP compound

Abstract

The first-principles calculations based on density functional theory (DFT) with the Hubbard U correction and Monte Carlo simulations have been used to study the structural, electronic, magnetic, mechanical, thermal, thermoelectric, optical, thermodynamic properties and magnetocaloric effect of the MnCoP compound. The structural analysis reveals that the compound is stable in its ferromagnetic configuration. As a result, our optimized lattice parameters are in good agreement with those obtained experimentally. Additionally, calculations of electronic band structure, total density (TDOS) and partial density (PDOS) of electronic states revealed that the compound behaves as a metal. Our compound is dynamically, mechanically and thermodynamically stable, as shown by the calculated phonon dispersion curves, elastic constants and negative formation energy. The MnCoP is a ductile material with a metallic bond, according to calculations of Poisson’s ratio and Pugh’s ratio. To describe the thermal behavior of this compound, transport properties including the figure of merit (ZT), thermal (k/τ) and electrical conductivities (σ/τ), power factor (PF) and Seebeck coefficient (S) were calculated. Furthermore, optical properties such as 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) are examined. We have also employed the quasi-harmonic Debye model to investigate the thermodynamic properties. Based on the metallic nature and ferromagnetic properties, it is expected that this compound is a suitable material for spintronics, optoelectronics, and TE devices. Finally, we investigate the influence of the external magnetic field on the magnetic phase transitions, critical temperature, magnetization and specific heat capacity at a constant pressure of this material. Magnetic entropy and relative cooling capacity for different external magnetic fields are obtained around the critical temperature.