The study of electronic, elastic, magnetic and optical response of Zn1-xTixY (Y = S, Se) through mBJ potential

Abstract

To explore the structural, electronic, magnetic and optical properties of Zn1-xTixY (Y=S, Se) alloys, in the composition range 0 ≤ x ≤ 1, we have applied full-potential linearized augmented plane wave plus local orbital (FP-LAPW + lo) scheme, which is based on the density functional theory (DFT). Structural optimizations have been done in ferromagnetic (FM) and antiferromagnetic (AFM) phase by using Wu–Cohen generalized gradient approximation (WC-GGA), whereas recently developed modified Becke and Johnson (mBJ) potential was employed to study electronic and optical properties. The lower value of ground state energy and negative enthalpy of formation confirm stability in the FM phase. Due to the spin polarization of electrons in the Ti-d orbital, origin of half-metallic ferromagnetism has been expressed by the calculated band structures, electronic density of states (DOS) and magnetic moments. We also have calculated the exchange splitting energy Δx (d), crystal field energy (ΔEcrystal = Et2g−Eeg) and exchange constants (N0α and N0β). The negative value of exchange constant (N0β) and large splitting of 3d-states of Ti show that the down spin potential is more effective than up spin. Finally, the results of optical parameters such as complex dielectric constant ε (ω), refractive index n (ω), normal incident reflectivity R (ω), absorption coefficient ɑ (ω), optical conductivity σ (ω) and optical loss factor L (ω) are discussed in the energy range 0–14 eV. Moreover, we have verified the Penn's model by showing the inverse relation between the static dielectric constant and the optical band gap. The direct relation between static dielectric constant and static refractive index has been observed by increasing the composition of Ti. The calculated parameters provide valuable theoretical information for optical and spintronics device applications.