First-principles evaluation of Co-doped ZnS and ZnSe ferromagnetic semiconductors.

In this study, we have employed first-principle calculations to investigate the structural, mechanical, electronic, magnetic and the optical properties of Co-doped ZnS and ZnSe compounds. The ferromagnetic structural stability is determined from the calculated total energy difference between ferromagnetic and antiferromagnetic phases. The calculated mechanical properties show that these materials are mechanically stable, ductile and anisotropic. The modified Becke-Johnson local density approximation functional is used for accurate prediction of the electronic properties of Co-doped ZnS and ZnSe. The electronic band structures and density of states plots reveal ferromagnetic semiconducting behavior in these compounds, which is explained in terms of exchange and crystal field splitting energies, exchange constants and magnetic moments. The optical properties have been studied systematically by computing parameters like real and imaginary part of the dielectric constant, refractive index, extinction and absorption coefficients, optical conductivity, reflectivity and energy loss function. The tuning of band gap from ultraviolet to visible region with minimum optical loss, due to the Co doping, makes these materials suitable candidates for optoelectronic device fabrications. [ABSTRACT FROM AUTHOR]