Structural, Thermodynamic and Magneto-Electronic Properties of Cd0.75Cr0.25Se and Zn0.75Cr0.25S: An Ab-Initio Study

Abstract

Using the full-potential linearized augmented plane wave plus local orbital method based on spin-polarized density functional theory, we investigate the parameters of the structure, the electronic, magnetic, and thermodynamic properties of cubic zinc–blende Cd_0.75Cr_0.25Se and Zn_0.75Cr_0.25S ordered ferromagnetic materials. We adopt the Perdew–Burke–Ernzerhof generalized gradient approximation and the modified Becke-Johnson exchange potential for the exchange–correlation energy and potential. Furthermore, the effect of high pressure on the normalized unit cell volume, bulk modulus, and Grüneisen parameter for both CdSe and ZnS binary compounds as well as for Cd_0.75Cr_0.25Se and Zn_0.75Cr_0.25S partially substituted materials was also predicted. The results indicate that both these materials are stabilized in the ferromagnetic phase. Using the modified Becke–Johnson approach and Perdew–Burke–Ernzerhof generalized gradient approximation, our calculations also demonstrate that both Cd_0.75Cr_0.25Se and Zn_0.75Cr_0.25S alloys are semiconductors with the magnetic moment of 4 μ_B per formula unit. Furthermore, the calculations of the s–d exchange constant and p–d exchange constant clearly indicate the magnetic nature of these compounds. Finally, in order to gain further information, basic thermodynamic properties such as heat capacity, thermal expansion coefficient, and entropy have been explored using the quasi-harmonic Debye model.