(Funded by the U.S. Department of Defense, the U.S. Department of Energy, and the U.S. National Science Foundation)
Researchers from the Massachusetts Institute of Technology, Purdue University, Stanford University, Rice University, and the U.S. Department of Energy’s Lawrence Berkeley National Laboratory, Argonne National Laboratory, and Oak Ridge National Laboratory have described how a type of quasiparticle, called a polaron, behaves in tellurene, a nanomaterial made up of tiny chains of tellurium atoms. A polaron forms when charge-carrying particles such as electrons interact with vibrations in the atomic or molecular lattice of a material. The researchers had hypothesized that as tellurene transitions from bulk to nanometer thickness, polarons change from large, spread-out electron-vibration interactions to smaller, localized interactions. Computations and experimental measurements backed up this scenario.

(Funded by the U.S. Department of Energy and the U.S. Department of Defense)
Researchers from Columbia University, the University of Chicago, the University of Vienna in Austria, Politecnico di Milano in Italy, and Universita Degli Studi Dell’ Aquila in Italy have created a device that can generate photon pairs more efficiently than previous methods while being less prone to error. To create the device, the researchers used thin crystals of a van der Waals semiconducting transition metal called molybdenum disulfide. Then, they layered six of these crystal pieces into a stack, with each piece rotated 180 degrees relative to the crystal slabs above and below. As light travels through this stack, a phenomenon called quasi-phase-matching manipulates properties of the light, enabling the creation of paired photons. “We believe this breakthrough will establish van der Waals materials as the core of next-generation nonlinear and quantum photonic architectures,” said James Schuck, one of the scientists involved in this study.

(Funded by the U.S. Department of Energy)
Researchers from the U.S. Department of Energy’s Argonne National Laboratory and the University of Cambridge have unveiled the existence of an intriguing link between ferroelectric domain walls and electron interactions in a type of van der Waals 2D material. A domain wall is a boundary or interface separating regions inside a material that exhibit different orientations of ferroelectric polarization. The link discovered by the researchers gives rise to a new type of superconductivity that is unique to these 2D materials. “We showed that places like domain walls, typically associated with irregularities and potentially harmful for things like superconductivity, can indeed be helpful for superconductivity,” said Gaurav Chaudhary and Ivar Martin, the two authors of this study.

(Funded by the U.S. Department of Energy)
Researchers from the U.S. Department of Energy’s SLAC National Accelerator Laboratory, Stanford University, and the University of California, Davis, have developed a new software tool that can provide more quantitative details about the structure of the active sites in single atom catalysts in much less time, compared to current methods. Normally, a catalyst uses an inert support to stabilize nanometer-sized clusters of metal atoms, or metal nanoparticles. To maximize the use of each metal atom, researchers also use single atom catalysts, where individual metal atoms are dispersed onto the support. In reality, catalysts usually have both single atoms and nanoparticles, and the new software tool determines the fractions of these two forms.

(Funded by the U.S. Department of Energy, the U.S. Department of Defense, and the U.S. National Science Foundation)
Scientists from Oregon State University; the Molecular Foundry at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory; Columbia University; and the Autonomous University of Madrid, Spain, have discovered luminescent nanocrystals that can be quickly toggled from light to dark and back again. “Normally, luminescent materials give off light when they are excited by a laser and remain dark when they are not,” said Artiom Skripka, one of the scientists involved in this study. “In contrast, we were surprised to find that our nanocrystals live parallel lives. Under certain conditions, they show a peculiar behavior: They can be either bright or dark under exactly the same laser excitation wavelength and power.”