Structural, Electronic, Magnetic, Elastic, Thermodynamic, and Thermoelectric Properties of the Half-Heusler RhFeX (with X = Ge, Sn) Compounds

Abstract

In the present work, the structural, electronic, magnetic, elastic, thermodynamic, and thermoelectric properties of half-Heusler alloys RhFeX (with X = Ge, Sn) have been investigated using the full-potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT) implemented in the WIEN2k code. The generalized gradient approximation of Perdew-Burke-Ernzerhof (GGA-PBE) and the Tran-Blaha-modified Becke-Johnson exchange potential method (TB-mBJ) has been used for modeling exchange correlation potential. The results obtained show that the two studied compounds are mechanically and dynamically stable. On the other hand, both compounds RhFeX (with X = Ge, Sn) exhibit a half-metallic ferromagnet behavior; their magnetic moments obey the Slater-Pauling rule with an absolute bias of 100% around the Fermi level. The thermodynamic properties including the isothermal bulk modulus, the heat capacity, the Debye temperature, and the thermal expansion coefficients of both compounds are investigated using the quasi-harmonic Debye model. According to the thermoelectric results, the values of the merit factor (ZT) are 0.935 and 0.952 at 300 K for RhFeGe and RhFeSn, respectively; these results indicate that our compounds are potentially good candidates for thermoelectric applications at low temperature.