Electronic, elastic, and thermodynamic properties of Cd0.75TM0.25S (TM = Os or Ir) alloys with the TB-mBJ approach and hybrid density functional (HSE06)

Abstract

The electronic structure, elastic moduli, as well as thermodynamic features of the ferromagnetic Cd_0.75TM_0.25S (TM = Os or Ir) compounds in the zinc-blende phase were investigated by employing the “generalized gradient approximations” parametrized by Wu and Cohen combined with the “modified Becke-Johnson (TB-mBJ)” as well as the hybrid functional (HSE06). The predicted total magnetic moments for the transition metals Os and Ir are 4.0 μB and 3.0 μB with TB-mBJ and are 2.0 μB and 3.0 μB using the hybrid functional (HSE06) for compounds Cd_0.75Os_0.25S and Cd_0.75Ir_0.25S, respectively. The generation of magnetic moments and spin-polarization in these alloys is directly linked to the contribution coming from TM-5d states. The ferromagnetic properties of these alloys were predicted by the computed exchange constants Besides, the increase in the porosity paramete\(N_{0\alpha }\) and \(N_{0\beta }\). The Total and partial densities of states (TDOS/PDOS) and the behavior of electronic band structures (EBS) were also calculated to describe the ferromagnetic semiconducting and half-metallic (HM) characteristics with TB-mBJ and the hybrid functional (HSE06). According to the findings, Cd_0.75Os_0.25S is a half-metallic ferromagnetic (HM) material with a full polarization spin distribution of electrons at the Fermi energy level, exhibiting metallicity for the majority spin and a semiconducting nature for the minority spin. In contrast, Cd_0.75Ir_0.25S is a ferromagnetic half-semiconductor (HSC) with two distinct gaps depending on the up and down spin configurations. Calculations of the elastic constants, Young and shear moduli reveal that the compound Cd_0.75TM_0.25S (TM = Os or Ir) is mechanically stable, has a high degree of anisotropy, and is naturally ductile. Furthermore, the “quasi-harmonic Debye model” was performed to examine the thermodynamic properties of the studied compounds, including the thermal capacity, entropy and Debye temperature.