Shell-mediated control of surface chemistry of highly stoichiometric magnetite nanoparticles.

Magnetite (Fe3O4) nanoparticles are one of the most studied nanomaterials for different nanotechnological and biomedical applications. However, Fe3O4 nanomaterials gradually oxidize to maghemite (γ-Fe2O3) under conventional environmental conditions leading to changes in their functional properties that determine their performance in many applications. Here we propose a novel strategy to control the surface chemistry of monodisperse 12 nm magnetite nanoparticles by means of a 3 nm-thick Zn-ferrite epitaxial coating in core/shell nanostructures.

Magnetic interactions in the S = 1/2 square-lattice antiferromagnets BaCuTeO and BaCuWO: parent phases of a possible spin liquid.

The isostructural double perovskites BaCuTeO and BaCuWO are shown by theory and experiment to be frustrated square-lattice antiferromagnets with opposing dominant magnetic interactions. This is driven by differences in orbital hybridisation of Te and W. A spin-liquid-like ground state is predicted for BaCu(TeW)O solid solution similar to recent observations in SrCu(TeW)O.

Thermal Transport and Phonon Hydrodynamics in Strontium Titanate.

We present a study of thermal conductivity, κ, in undoped and doped strontium titanate in a wide temperature range (2-400 K) and detecting different regimes of heat flow. In undoped SrTiO_{3}, κ evolves faster than cubic with temperature below its peak and in a narrow temperature window. Such behavior, previously observed in a handful of solids, has been attributed to a Poiseuille flow of phonons, expected to arise when momentum-conserving scattering events outweigh momentum-degrading ones.