News by Subject Chemistry & Physics

Atomic-scale optical spectroscopy revealed huge Raman scattering when an atomic point contact is formed between a plasmonic silver tip and a single-crystal silicon surface. The huge Raman scattering allows to observe selectively surface phonons of the single-crystal silicon and to resolve the atomic-scale structures. Atomic point contact Raman scattering paves the way for ultrasensitive atomic-scale vibrational spectroscopy to investigate surface structures.

An international team of researchers led by physicists from the University of Oldenburg (Germany) has succeeded in generating an unusual quantum state in charge carrier complexes that are closely linked to light particles and located in ultrathin semiconductor sheets. The team reports in the journal Nature Materials that this process produces light similar to that of a laser. The phenomenon could be used to create the smallest possible solid-state lasers.

In spintronics, the magnetic moment of electrons is used to transfer and manipulate information. An ultra-compact 2D spin-logic circuitry could be built from 2D materials that can transport the spin information over long distances and provide strong spin-polarization of charge current. Experiments by physicists suggest that magnetic graphene can be the ultimate choice for these 2D spin-logic devices as it efficiently converts charge to spin current and can transfer this strong spin-polarization over long distances.

Ring microlasers are eyed as potential light sources for photonic applications, but they first must be made more powerful. Combining multiple microlasers into an array solves only half of the problem, as this adds noisy "modes" to the resulting laser light. Now, thanks to the math behind supersymmetry theory, Penn Engineers have achieved single-mode lasing from such an array. By calculating the necessary properties for "superpartner" arrays, they can cancel out the unwanted extra modes.

2D superconductors have drawn considerable attention both for the fundamental physics they display as well as for potential applications in fields such as quantum computing. Although considerable efforts have been made to identify them, materials with high transition temperatures have been hard to find. Materials featuring both superconductivity and non-trivial band topology have proven even more elusive. A recent Nano Letters paper predicts just such a material in the easily exfoliable, topologically non-trivial semimetal W2N3.