Structural and magnetic properties of Sn_0.95Co_0.05O₂ nanocrystalline and diluted magnetic semiconductors have been investigated. This sample has been synthesized by co-precipitation route. Study of magnetization hysteresis loop measurements infer that the sample of Sn_0.95Co_0.05O₂ nanoparticle shows a well-defined hysteresis loop at 300 K temperature, which reflects its ferromagnetic behaviour. We confirmed the room-temperature intrinsic ferromagnetic (FM) semiconductors by ab initio calculation, using the theory of the functional of density (DFT) by employing the method of Korringa–Kohn–Rostoker (KKR) as well as coherent potential approximation (CPA, explain the disorder effect) to systems. The ferromagnetic state energy was calculated and compared with the local-moment-disordered (LMD) state energy for local density approximation (LDA) and LDA–SIC approximation. Mechanism of hybridization and interaction between magnetic ions in Sn_0.95Co_0.05O₂ is also investigated. To explain the origin of ferromagnetic behaviour, we give information about total and atoms projected density of state functions.

Using ab initio calculations, we predict the improvement of the desorption temperature and the hydrogen storage properties of doped Mg-based hydrides such as,Mg₁₅AMH₃₂ (AM = Ca, Sr and Ba) as a super cell 2 × 2 × 2 of MgH₂. In particular, the electronic structure has been obtained numerically using the all-electron full-potential local-orbital minimum-basis scheme FPLO9.00-34. Then, we discuss the formation energy calculations in terms of the material stabilities and the hydrogen storage thermodynamic properties improvements. Among others, we find that the stability and the temperature of desorption decrease without reducing significantly the high storage capacity of hydrogen. Moreover, it has been observed that such a doping procedure does not affect the electronic behavior as seen in MgH₂, including the insulator state in contrast with the transition metal hydrides, which modify the electronic structure of pure MgH₂.

The self-consistent ab-initio calculations, based on density functional theory approach and using the full potential linear augmented plane wave method, are performed to investigate both electronic and magnetic properties of the MnB₂ compounds. Polarized spin and spin–orbit coupling are included in calculations within the framework of the ferromagnetic state between two adjacent Mn atoms. Magnetic moment considered to lie along the (001) axes are computed. The antiferromagnetic and ferromagnetic energies of MnB₂ systems are obtained. Obtained data from ab-initio calculations are used as input for the high-temperature series expansions (HTSEs) calculations to compute other magnetic parameters. The exchange interactions between the magnetic atoms Mn–Mn in MnB₂ are established by using the mean field theory. The HTSEs of the magnetic susceptibility with the magnetic moments in MnB₂ (𝑚_Mn) through Ising model is given. The critical temperature 𝑇_C (K) is obtained by HTSEs applied to the magnetic susceptibility series combined with the Padé approximant method. The critical exponent 𝛾 associated with the magnetic susceptibility is deduced as well.