Cooperative Dynamics of Highly Entangled Linear Polymers within the Entanglement Tube.

We present a quantitative comparison of the dynamic structure factors from unentangled and strongly entangled poly(butylene oxide) (PBO) melts. As expected, the low molecular weight PBO displays Rouse dynamics, however, with very significant subdiffusive center-of-mass diffusion. The spectra from high molecular weight entangled PBO can be very well described by the dynamic structure factor based on the concept of local reptation, including the Rouse dynamics within the tube and allowing for non-Gaussian corrections.

Magnetostriction-Driven Muon Localization in an Antiferromagnetic Oxide.

Magnetostriction results from the coupling between magnetic and elastic degrees of freedom. Though it is associated with a relatively small energy, we show that it plays an important role in determining the site of an implanted muon, so that the energetically favorable site can switch on crossing a magnetic phase transition. This surprising effect is demonstrated in the cubic rocksalt antiferromagnet MnO which undergoes a magnetostriction-driven rhombohedral distortion at the Néel temperature T_{N}=118  K.

Probing spin waves in CoO nanoparticles for magnonics applications.

The magnetic properties of spinel nanoparticles can be controlled by synthesizing particles of a specific shape and size. The synthesized nanorods, nanodots and cubic nanoparticles have different crystal planes selectively exposed on the surface. The surface effects on the static magnetic properties are well documented, while their influence on spin waves dispersion is still being debated.

Structural insight into the cooperativity of spin crossover compounds.

Spin-crossover (SCO) compounds are promising materials for a wide variety of industrial applications. However, the fundamental understanding of their nature of transition and its effect on the physical properties are still being fervently explored; the microscopic knowledge of their transition is essential for tailoring their properties. Here an attempt is made to correlate the changes in macroscopic physical properties with microscopic structural changes in the orthorhombic and monoclinic polymorphs of the SCO compound Fe(PM-Bia)(NCS) (PM = N-2'-pyridylmethylene and Bia = 4-aminobiphenyl) by employing single-crystal X-ray diffraction, magnetization and DSC measurements.

Signature of antiphase boundaries in iron oxide nanoparticles.

Iron oxide nanoparticles find a wide variety of applications, including targeted drug delivery and hyperthermia in advanced cancer treatment methods. An important property of these particles is their maximum net magnetization, which has been repeatedly reported to be drastically lower than the bulk reference value. Previous studies have shown that planar lattice defects known as antiphase boundaries (APBs) have an important influence on the particle magnetization.

Soliton-Mediated Magnetic Reversal in an All-Oxide-Based Synthetic Antiferromagnetic Superlattice.

All-oxide-based synthetic antiferromagnets (SAFs) are attracting intense research interest due to their superior tunability and great potentials for antiferromagnetic spintronic devices. In this work, using the LaCaMnO/CaRuTiO (LCMO/CRTO) superlattice as a model SAF, we investigated the layer-resolved magnetic reversal mechanism by polarized neutron reflectivity. We found that the reversal of LCMO layer moments is mediated by nucleation, expansion, and shrinkage of a magnetic soliton.

Magnetic Field-Assisted Chemical Vapor Deposition of Iron Oxide Thin Films: Influence of Field-Matter Interactions on Phase Composition and Morphology.

Magnetic field-assisted CVD offers a direct pathway to manipulate the evolution of microstructure, phase composition, and magnetic properties of the as-prepared film. We report on the role of applied magnetic fields (0.5 T) during a cold-wall CVD deposition of iron oxide from [Fe(OBu)] leading to higher crystallinity, larger particulates, and better out-of-plane magnetic anisotropy, if compared with zero-field depositions.

Novel Melt-Spun Polymer-Optical Poly(methyl methacrylate) Fibers Studied by Small-Angle X-ray Scattering.

The structural properties of novel melt-spun polymer optical fibers (POFs) are investigated by small-angle X-ray scattering. The amorphous PMMA POFs were subjected to a rapid cooling in a water quench right after extrusion in order to obtain a radial refractive index profile. Four fiber samples were investigated with small-angle X-ray scattering (SAXS).