Density Functional Studies of Electronic, Magnetic, Optical and Elastic Properties of Strongly Systems

Abstract

This research is focused on the first principle calculations of electronic, magnetic, optical and elastic properties of materials of spintronics and electronics interest. Full potential linearized augmented plane wave method (FP-LAPW) method and linear combinations of atomic orbital (LCAO) technique, as implemented in WIEN and ADF-BAND codes, are employed for the study. These methods are well tested and among best methods to solve Kohn-Sham density functional theory. A series of potassium rare earth sulphides KMS2 has been investigated for electronic band structure, magnetism and optical properties. The KErS2, KHoS2 and KNdS2 are found to be ground state ferromagnetic wide band gap semiconductor while KLuS2 is non-magnetic wide band gap semiconductor. These materials are potential candidate for spintronics and optoelectronic industry applications. Further Mn doped CdS has been studied for electronic structure and magnetism. It is found that Mn doped CdS is half metallic ferromagnetic system with magnetic moment of 4.21 μB. Also the MCA and exchange splitting constants Noα and Noβ confirm that ferromagnetism exists in Mn:CdS. Hence, the material is useful for magneto-optical devices. PrCrO3 is cubic perovskite material having application in spintronics. A comparative study of the two techniques: L FP-LAPW and LCAO, has been performed. Otherwise equivalent approaches are observed to depend sensitively on Hubbard U parameter which is different for the two techniques. Zn3V2O8 is revealed to be a wide band gap semiconductor with high absorption coefficient in ultraviolet region. LBMO is synthesized by hydrothermal method and electronic structure, and magnetism are studied. A transition from ferromagnetic to anti-ferromagnetic phase is observed on increasing concentration from 0.55 of Ba. This happens due to the lowering of Mn3+ in proportion to Mn4+. Cubic phase of LMO is synthesized by hydrothermal process, and lattice parameter thus obtained is used to further investigate elastic and electronic properties under stress. A half-metal to metal transition is observed at 40 GPa. Doping of Tm in ZnS decreases the band gap and we get a ground state ferromagnetic system. This study is an endeavor in the deep understanding of electronic structure, magnetism, optical phenomena and elastic properties of strongly correlated systems of spintronics and opto-electronic interest.