Controlling vortex circularity and polarity

Magnetic vortices are of high interest in basic and applied research, e.g. for possible applications in data storage, signal transfer, logic devices, etc. They can be described by the polarity of the central core (with the magnetization pointing "up" or "down") and their circularity (rotational direction of the magnetization around the central core). If it were possible to manipulate both properties independently, two bits could be realized by one such nano-dot with a vortex, similar to our approaches utilizing fourfold nanomagnets.

High symmetry gadolinium(III) polyhedra

In a recent article, creation of hollow nanospheres Gd20, Gd32, Gd50 and Gd60 is described using the approach to assemble fragments containing different polygons. While structural analysis revealed the symmetries of the respective nanospheres, magnetic studies show in theory and experiment that these polyhedra show antiferromagnetic interaction which can be attributed to classical spins at the Gd sites. Magnetic measurements can even be used as "fingerprints" to identify the polyhedra.

Collective magnetic properties of iron oxide nanoparticle-clusters

Block copolymers can be used as “containers” which can be filled, e.g., by drugs, dyes, nanoparticles etc. Such polymeric containers can also contain ordered clusters of nanoparticles – with possibly novel collective properties, different from those of single nanoparticles and bulk material.

In a recent study, FeO_x nanoparticles of diameter 8 nm were encapsulated in such a block copolymer with ratios of polymer:nanoparticle between 20:1 and 400:1. Additionally, hybrid nanomaterials combining FeO_x with quantum dots, quantum rods, gold nanoparticles etc. were produced.