Strange new materials experimentally identified just a few years ago are now driving research in condensed-matter physics around the world. Tthese "strong 3-D topological insulators" - TIs for short - are seemingly mundane semiconductors with startling properties. Topological insulators offer unique opportunities to control electric currents and magnetism, and are promising materials for future spintronic applications or could provide access to novel, fascinating physical phenomena. While so far, only synthetic TIs had been experimentally identified, researchers in Germany report the discovery of a natural occurring topological insulator: the mineral Kawazulite.
A control over spin-electron interactions is vital for development of spintronic devices and for quantum computation. When a magnetic impurity is surrounded by free electrons, a realignment of the electron spins occurs below a critical temperature due to spin-electron interactions; this causes an increase in resistivity of the material - a phenomenon known as the "Kondo" effect. The Kondo effect has been observed in a wide range of systems including single atoms/molecules, quantum-dots, and carbon nanotubes, however two-dimensional molecular Kondo systems have yet to be explored. Molecules with magnetic properties recently have great appeal as they offer an ideal platform to advance the fundamental understanding of spin related mechanisms, and can act as templates for molecular spintronic device fabrication due to their propensity for spontaneous self assembly. By manipulating nearest-neighbor molecules with a scanning tunneling microscope tip researchers now were able to tune the spin-electron coupling of the center molecule inside a small hexagonal molecular assembly in a controlled step-by-step manner. This variation of Kondo effect might be useful for instance for storing or manipulating data in spintronic memory devices.
Spintronics (short for "spin-based electronics") is an emergent technology which exploits the quantum propensity of electrons to spin as well as making use of their charge state. The field of spintronics got started in 1988 with the discovery ("Giant Magnetoresistance of (001)Fe/(001)Cr Magnetic Superlattices") of giant magnetoresistance effect in magnetic multilayers in which a single dimension was reduced to the nanometer range. The field was then extended to structures with two reduced dimensions like nanowires and nanopillars or nanotubes. Today, a challenge for spintronics is the study of spin transport properties in structures based on zero-dimensional elements in which the three dimensions have been reduced. So far, very few techniques allow to contact a single isolated nanometer sized object to study the effect of confinement on spin transport. Researchers in France now describe the experimental achievement of a technique that allows to inject and detect spins in a single isolated nanometer-sized cluster. They fabricated nanometer-sized magnetic tunnel junctions using a conductive tip nanoindentation technique in order to study the transport properties of a single metallic nanoparticle.
A recent study shows that just by changing the structure of a molecule, without altering its chemical composition, can lead to a variation in the spin-electron interaction strength, and consequently the associated Kondo temperatures.