The Density Functional Study of Structural, Electronic, Magnetic and Thermodynamic Properties of XFeSi (X = Gd, Tb, La) and GdRuSi Compounds

The structural, electronic, magnetic, and thermodynamic properties of XFeSi (X = Gd, Tb, La) and GdRuSi compounds are investigated using density functional theory by the WIEN2k code. Using the first-principle procedure, the Hubbard parameter of Gd and Tb 4f electrons and La 5d electrons of XFeSi (X = Gd, Tb, La) and GdRuSi compounds is calculated. The structural and electronic and magnetic properties of these compounds within GGA and GGA + U approaches in the presence of spin-orbit coupling are calculated and compared. The calculated results indicate that the ferromagnetic phase is the most stable phase of XFeSi (X = Gd, Tb) and GdRuSi compounds and the nonmagnetic phase is the stable phase of LaFeSi. The magnetic moment of GdFeSi, GdRuSi, and TbFeSi compounds is due to Gd and Tb atoms. The calculated electronic band structures of these compounds show that these compounds have metallic behavior. Furthermore, the thermodynamic properties of these compounds using the quasi-harmonic Debye model as a function of temperature and pressure within GGA and GGA + U approaches are investigated.