Structural, magnetic, and optoelectronic properties of new ferromagnetic semiconductors Cd0.75Os0.25S and Cd0.75Ir0.25S: Insight from DFT computations

摘要

This paper investigates in detail the structural, magnetic, and optoelectronic properties of Cd0.75TM0.25S (TM = Os and Ir) alloys having a zinc-blende structure of the ferromagnetic phase using the full potential linearized augmented plane-wave (FP-LAPW) method as implemented in the Wien2k package. The exchange-correlation potential was treated with the generalized gradient approximation (GGA). Moreover, the GGA +U + SO approximation (where U denotes the Hubbard Coulomb energy and SO is the spin orbit coopling) are employed to treat the d electrons properly. The analysis of the values of formation energy, formation enthalpy, phonon spectra and the exchange interaction parameters show that the investigated alloys are stable and can be synthesized. The densities of states (DOS) indicate that Cd0.75TM0.25S (TM = Os and Ir) exhibits metallic nature using both GGA and GGA + SO. The half-metallic nature for Cd0.75Os0.25S and the ferromagnetic half-semiconductor nature for Cd0.75Ir0.25S have been predicted by GGA +U. Both considered alloys become ferromagnetic-semiconductors by using GGA + SO +U, where the computed band gaps are 0.52 for Cd0.75Os0.25S and 0.72 for Cd0.75Ir0.25S. The dielectric function's real and imaginary portions epsilon'(omega),epsilon ''(omega), absorption coefficient alpha(omega), and refractive index n(omega) were evaluated using a radiation range up to 30 eV. For CdS, the observed results are on par with previously published experimental and theoretical results. Our findings imply that these materials might be of potential use in future spintronic devices.