Basic science

For the first time, researchers from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), Dartmouth College, Penn State, the University of California, Merced, and Université Catholique de Louvain in Belgium have demonstrated an approach that combines high-throughput computation and atomic-scale fabrication to engineer high-performance quantum defects.

Researchers from North Carolina State University, the Leibniz Institute of Polymer Research Dresden in Germany, Technische Universität Dresden in Germany, and Otto von Guericke University Magdeburg in Germany have embedded gold nanorods in hydrogels that can be processed through 3D printing to create structures that contract when exposed to light and expand when the light is removed. When the hydrogel structures are exposed to light, the embedded gold nanorods convert that light into heat.

Scientists from the U.S. Department of Energy’s Pacific Northwest National Laboratory have discovered that reducing graphene oxide membranes with ultraviolet light alters the oxygen functional groups on the graphene oxide surface. This modification results in a novel separation mechanism that is selective for charge rather than size. Exposure to ultraviolet light selectively removed hydroxyl groups from the graphene oxide planes, leading to enhanced interactions of metal cations with functional groups located at the edges of the graphene oxide.

Researchers from the University of California San Diego have developed an innovative approach to multispectral photodetection by alternating layers of graphene and colloidal quantum dots. By carefully engineering the material stack, the researchers created photodetectors sensitive to different wavelength bands without additional optical components. The key innovation lies in using graphene monolayers as independent charge collectors at different depths within a quantum dot absorber layer.

Researchers from Florida State University, the University of California Santa Barbara, Tsinghua University in China, Leipzig University in Germany, and Stuttgart University in Germany have identified, for the first time, the existence of local collective excitations of #electrons, called #plasmons, in a #Kagome metal – a class of materials whose atomic structure follows a hexagonal pattern that looks like a traditional Japanese basket weave – and found that the wavelength of those plasmons depends upon the thickness of the metal.

Scientists from the Massachusetts Institute of Technology, Arizona State University, the U.S. Department of Energy’s Brookhaven National Laboratory, Sorbonne University in Paris, France, and Utrecht University in the Netherlands have reported new insights into exotic particles that are key to a form of magnetism that originates from ultrathin materials only a few atomic layers thick. The scientists identified the microscopic origin of these particles, known as excitons, and showed how they can be controlled by chemically “tuning” the material, which is primarily composed of nickel.

Scientists from the U.S. Department of Energy's (DOE) Argonne National Laboratory (ANL) and the University of Chicago have developed a new technique to determine how nanoparticles move and interact with one another in soft matter when subjected to an applied force or temperature change. At the start, three bands of nanoparticles formed: fast moving, slow moving, and static. After 15 seconds, the fast-moving band vanished. About 40 seconds later, the three bands returned.

Physicists from Purdue University, Washington University in St. Louis, and the U.S. Department of Energy’s Sandia National Laboratories have levitated a fluorescent nanodiamond and spun it at incredibly high speeds (up to 1.2 billion times per minute). The fluorescent diamond emitted and scattered multicolor lights in different directions as it rotated. When illuminated by a green laser, the nanodiamond emitted red light, which was used to read out its electron spin states. An additional infrared laser was shone at the levitated nanodiamond to monitor its rotation.

University of California, Irvine scientists have discovered a one-dimensional nanoscale material whose color changes as temperature changes. "We found that we can make really small and sensitive thermometers," said Maxx Arguilla, one of the scientists involved in this study. Arguilla likened the thermometers to "nano-scale mood rings," referring to the jewelry that changes color depending on the wearer's body temperature.

Researchers from Cornell University have used solubility rather than entropy to overcome thermodynamic constraints and create high-entropy oxide nanocrystals at lower temperatures. High-entropy materials are formed by mixing five or more elements within the structure of a crystal.