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Magnetic, Superconducting and nearly Semiconducting? How is that Possible?

A material that is magnetic, superconducting and behaves nearly like a semiconducting sounds fairly unusual, and it is. Just such a material, made from potassium, iron and selenium, was recently discovered. It has similar superconducting properties to iron-arsenide-based superconductors. However, it is also nearly semiconducting and, most curious, has a very high (antiferro-)magnetic ordering temperature with large (rather than small) magnetic moments.

Standing Ribbons on Edge Leads to Transparent Triumph

A novel electrode architecture has led to a new way to make transparent electrical contacts. Typical ways of attaching a conductor to a non-metallic material allow you to see the electrode. However, for many applications, like light emitting diode (LED) displays, smart windows and solar cells, transparency to visible light is a requirement that conflicts with electrical conductance. Thinner films are more transparent, but less conductive. The new architecture consists of specially patterned nanoscale-thick metallic ribbons, standing on edge, supported by a polymer matrix.

Defect Detective

An international team of researchers has discovered a new type of defect in an unconventional material known as a quasicrystal. Mysterious nanodomains observed on the surfaces of quasicrystals led to the discovery. Quasicrystals were already known to have a unique defect type, known as a phason flip, which can form at the surface. The new defect type is related, but unlike the phason flip is not restricted to the surface; it bridges the surface and the bulk.

Making Connections to Graphene

Graphene is supposed to have the potential to replace silicon in electronic devices, making them thinner and faster, but making such devices depends on making electrical contacts. Researchers have deposited two metals onto graphene — a one atom thick layer of carbon — to see what kinds of elements might work best. Metals like lead were predicted to attach weakly, while rare earth metals were predicted to stick strongly giving better results. Scanning tunneling microscopy experiments confirmed the predictions.

Same Charge, Different Response

Ions in water with the same charge, e.g. Fe3+ and La3+, behave dramatically differently at the air/water interface when interacting with a charged surface. This difference violates classic electrostatic theory. The distributions of specific ion types were determined with unprecedented precision using newly developed surface sensitive synchrotron x-ray scattering and spectroscopic techniques. The research team was able to use these results to verify their recently-developed theoretical model that takes into account both classical and effective quantum behavior.


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