Phase diagrams of the two-dimensional one-band t-t ′ Hubbard model are obtained within the two-patch and the temperature-cutoff many-patch renor-malization group approach. At small t ′ and at van Hove band fillings anti-ferromagnetism dominates, while with increasing t ′ or changing filling anti-ferromagnetism is replaced by d-wave superconductivity. Near t ′ = t/2 and close to van Hove band fi...

Based on the ab initio electronic structure calculations the picture of ferromagnetism in polimerized C60 is proposed which seems to explain the whole set of controversial experimental data. We have demonstrated that, in contrast with cubic fullerene, in rhombohedral C60 the segregation of iron atoms is energetically unfavorable which is a strong argument in favor of intrinsic character of carb...

In this paper we have studied Structural, local structural and magnetic properties of sol-gel derived Zn1-xFexO (0≤x≤0.06) nanoparticles. The crystalline structure and crystallite size have been estimated by X-ray diffraction with Rietveld refinement and high-resolution transmission electron microscopy (HRTEM). Other structural and local structural properties have been studied by Extended X-ray...

Co-doped titanium dioxide (TiO2) nanorods with different doping concentrations were fabricated by a molten salt method. It is found that the morphology of TiO2 changes from nanorods to nanoparticles with increasing doping concentration. The mechanism for the structure and phase evolution is investigated in detail. Undoped TiO2 nanorods show strong ferromagnetism at room temperature, whereas inc...

The origin of ferromagnetism in semimagnetic III-V materials is discussed. The indirect exchange interaction caused by virtual electron excitations from magnetic impurity acceptor levels to the valence band can explain ferromagnetism in GaAs(Mn) in both degenerate and nondegenerate samples. Formation of ferromagnetic clusters and the percolation picture of phase transition describes well all av...

An ab initio linearized augmented plane-wave method has been employed to calculate the electronic and magnetic structures of both face-centered-cubic and body-centered-cubic Fe12xPdx alloys with x50.25, 0.50, and 0.75, respectively. Decreasing the Pd content in Fe12xPdx alloy from x51, the magnetic ordering of fcc Fe12xPdx changes from paramagnetism to ferromagnetism, ferrimagnetism, and finall...

Ferromagnetism is predicted in undoped diluted magnetic semiconductors illuminated by intense sub-band-gap laser radiation. The mechanism for photoinduced ferromagnetism is coherence between conduction and valence bands induced by the light which leads to an optical exchange interaction. The ferromagnetic critical temperature T(C) depends both on the properties of the material and on the freque...