Raman scattering provides significant information on the nature of the magnetic excitations of diluted magnetic semiconductors (DMS). Transitions involving an exchange of a quantum of angular momentum between the system and the radiation field result in Raman lines with shifts equal to the energy of the magnetic excitations in which the total spin of the crystal changes by fi. Such transitions ...

Recently a cluster Monte Carlo algorithm has been used very successfully in the two-dimensional Edwards-Anderson (EA) model. We show that this algorithm and a variant thereof can also be used successfully in models with a non-zero spin glass transition temperature. The application of such algorithms to the site-diluted EA model in three dimensions is discussed and the efficiency of the two algo...

Ti- and Nb- containing NiO catalysts have been synthesized by two different preparation methods: i) precipitation (Me-Ni-O oxides, Me = Nb or Ti), in order to prepare promoted catalysts; ii) wet impregnation on TiO2 NbOx supports, diluted/supported catalysts. The also characterized tested the oxidative dehydrogenation of ethane. catalytic performance Nb-promoted strongly depends composition, al...