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We have presented the results of detailed studies of oxygen vacancy and niobium (Nb) substituted spinel Li4Ti5O12 (LTO) materials using first-principles method within the framework of the density functional theory (DFT). We have shown that the ground state of oxygen vacancy and Nb substituted LTO is paramagnetic (PM), and the Nb substitution is most stable on the 16d sites of both the Li and Ti ions. We have indicated that the Nb substitution in the 16d site of Li ion become the n-type metallic material. But the oxygen vacancy containing NbT i substituted LTO is changed from the p-type to the n-type, as increased a concentration of Nb ions.

Herein, we have predicted the electronic and magnetic properties and magnetocrystalline anisotropy (MCA) of the most stabilized antiferromagnetic (AFM) ground state of bulk chalcopyrite (CuFeS$_{2}$) and films with various different thicknesses. We have shown that the easy axis of bulk structure is along the [001] direction and it agrees with the results of neutron measurements. For the CuFeS$_{2}$ film, our results have indicated that the ground state of ultra-thin film is ferromagnetic (FM) and the easy axis of ultra-thin film is in-plane. As increased the thickness of the film, its ground state becomes the AFM, and the easy axis is changed as out-plane. It may be a natural candidate material for integrating spintronics.