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sp–d exchange interaction was used to narrow the room-temperature band gap of zinc oxide films prepared by sol–gel method. Zinc oxide was doped with manganese ions by adding manganese chloride to the precursor and post-annealing in hydrogen. Films with different concentrations of manganese were prepared. Exchange interaction was established between the manganese ions in the lattice by introducing oxygen vacancies. The magnetic moment was found to increase with the concentration of manganese. For low concentrations of manganese, the band gap of the doped semiconductor was found to be wider than that of undoped ZnO films, in agreement with Vegard’s law. High concentrations of dopant resulted in a narrowing of the band gap. We ascribe the narrowing of the band gap to conduction band-edge Zeeman shifting. 12 at.% Mn was successfully substituted in ZnO films deposited by sol–gel method. Exchange interaction was established between the Mn ions through the mediation of oxygen vacancies. A narrowing of the band gap of ZnO was achieved by Zeeman shifting of the bottom of the conduction band.

Synchronized spin-valve oscillators may lead to nanosized microwave generators that do not require discrete elements such as capacitors or inductors. Uniformly magnetized oscillators have been synchronized, but offer low power. Gyrating magnetic vortices offer greater power, but vortex synchronization has yet to be demonstrated. Here we find that vortices can interact with each other through the mediation of antivortices, leading to synchronization when they are closely spaced. The synchronization does not require a magnetic field, making the system attractive for electronic device integration. Also, because each vortex is a topological soliton, this work presents a model experimental system for the study of interacting solitons.

Polymer-embedding of nano-sized indium tin oxide (SnO center dot In2O3, ITO) produces electrically conductive materials transparent to the visible light at filling factors higher than the percolation threshold. ITO powders are commercially available in an aggregated form and a disaggregation technique was required. Here, aggregated ITO nanoparticles were transformed to colloidal suspension by high-speed stirring. This finely dispersed ceramic suspension was stabilized by addition of poly(vinyl pyrrolidone) and the obtained colloidal system was cast on an optical-grade substrate (PET) to produce electrically conductive-transparent nanocomposite films. Preliminary mechanical and electrical characterization of these films showed good conductivity and interfacial properties.