Basic science

Researchers led by Cornell University have discovered an unusual phenomenon in Mott insulators, a metal-insulating material, providing valuable insights for the design of materials with new properties by way of faster switching between states of matter. Mott insulators are not fully understood, partly due to the challenging task of imaging the material's nanostructures in real space and capturing how these nanostructures undergo phase changes in as fast as a trillionth of a second. 

Researchers from Penn State have created a metasurface that can be used to preprocess and transform images before they are captured by a camera, allowing a computer – and artificial intelligence – to process them with minimal power and data bandwidth. A metasurface is an optical element akin to a glass slide that uses tiny nanostructures placed at different angles to control light. This new metasurface has many potential applications, including for use in target tracking and surveillance to map how a car, for example, moves across a city.

Researchers from the U.S. Naval Research Laboratory and Kansas State University have discovered slab waveguides based on the two-dimensional material hexagonal boron nitride. "We knew using hexagonal boron nitride would lead to outstanding optical properties in our samples; none of us expected that it would also act as a waveguide," said Samuel Lagasse, one of the scientists involved in the study. The slabs of hexagonal boron nitride were carefully tuned in thickness so that the emitted light would be trapped within the hexagonal boron nitride and waveguided.

Researchers from Harvard University and Utrecht University in The Netherlands have developed a previously elusive way to improve the selectivity of catalytic reactions, adding a new method of increasing the efficacy of catalysts for a potentially wide range of applications in various industries, including pharmaceuticals and cosmetics.

Physicists from the Massachusetts Institute of Technology have found that when five sheets of graphene are stacked like steps on a staircase, the resulting structure provides the right conditions for electrons to pass through as fractions of their total charge, with no need for any external magnetic field. The results are the first evidence of the "fractional quantum anomalous Hall effect" (the term "anomalous" refers to the absence of a magnetic field) in crystalline graphene, a material that physicists did not expect to exhibit this effect.

An international team of researchers from Princeton University, the University of Texas at Dallas, the National High Magnetic Field Laboratory in Tallahassee, FL, the Beijing Institute of Technology, and the University of Zurich in Switzerland has observed long-range quantum coherence effects in a topological insulator-based device, which may enable the development of efficient topological electronic devices.

Researchers at the Massachusetts Institute of Technology (MIT), using facilities at MIT and Harvard University’s Center for Nanoscale Systems (part of the National Nanotechnology Coordinated Infrastructure network), have demonstrated current-controlled, non-volatile magnetization switching in an atomically thin van der Waals magnetic material at room temperature. Magnets composed of atomically thin van der Waals materials can typically only be controlled at extremely cold temperatures, so the fact that the researchers were able to control these materials at room temperature is key.

Researchers from North Carolina State University, Arizona State University, Jeonbuk National University in South Korea, and Sungkyunkwan University in South Korea have discovered that liquid metal composites can spontaneously grow over four times in volume when exposed to water, while retaining metallic conductivity similar to their starting material. This growth occurs because water infiltration promotes oxidation reactions that generate porous gallium oxyhydroxide while freeing hydrogen gas.

Researchers from the University of Cincinnati and Texas A&M University have demonstrated a new chemical process that grafts nanotubes to copper, aluminum, gold, and other metal surfaces to create a strong, consistent, conductive link. Through computational calculations, the researchers have shown that carbon atoms in the link actually bond with two copper atoms, creating an especially strong bond.

Researchers from Rice University and Florida State University have shown that changing the structure of the oxide layer that coats aluminum nanoparticles modifies their catalytic properties. The researchers elucidated the structure of the native oxide layer on aluminum nanoparticles and showed that heating the nanoparticles to temperatures of up to 500 degrees Celsius (932 degrees Fahrenheit) in different gases can change the structure of the aluminum oxide layer.