Basic science

Researchers from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory, the University of California at Berkeley, the Massachusetts Institute of Technology, Arizona State University, and the National Institute for Materials Science in Tsukuba, Japan, have captured direct images of a new quantum phase of an electron solid – the Wigner molecular crystal. Whereas Wigner crystals are characterized by a honeycomb arrangement of electrons, Wigner molecular crystals have a highly ordered pattern of artificial “molecules” made of two or more electrons.

Researchers from Florida State University, the Shanghai Institute of Microsystem and Information Technology, and Wuhan University have revealed how various physical manipulations of graphene, such as layering and twisting, impact its optical properties and conductivity.

Cornell University researchers have made headway into understanding how twisted bilayer graphene becomes a superconductor. In 2023, the scientists developed a theoretical formalism to compute the highest possible superconducting transition temperature in any material obtained by stacking and twisting two-dimensional materials. For the current work, the scientists applied this theoretical formalism to twisted bilayer graphene. “One of the remarkable properties of twisted bilayer graphene is the associated tunability,” said Debanjan Chowdhury, one of the scientists involved in this study.

Researchers from New York University; the Center for Functional Nanomaterials (CFN), a U.S. Department of Energy Office of Science user facility at Brookhaven National Laboratory; and the National Institute for Materials Science in Tsukuba, Japan, have used a special robotic system to assemble very large pieces of atomically clean two-dimensional materials into stacks. These materials, called graphene heterostructures, consist of sheets just a few atoms thick, have record-setting dimensions – as large as 7.5 square millimeters, which is very large in the world of microelectronics.

Physicists at the Massachusetts Institute of Technology (MIT) have taken a key step toward solving the puzzle of what leads electrons to split into fractions of themselves. The new work is an effort to make sense of a discovery that was reported earlier this year by other physicists at MIT, who found that electrons appear to exhibit "fractional charge" in pentalayer graphene – a configuration of five graphene layers that are stacked atop a similarly structured sheet of boron nitride.

Researchers from the University of Illinois at Urbana-Champaign have discovered a new type of nanoparticle, palladium hydride, which contains palladium and hydrogen. Palladium hydride nanoparticles are typically structured symmetrically, looking like a cube with palladium atoms posted at each corner and centered on all six cubic faces. In contrast, the new nanoparticle’s structure is presumably the least symmetrical of all crystal systems.

Researchers from the U.S. Department of Energy’s Lawrence Livermore National Laboratory, Stanford University, and the University of Pennsylvania have developed a technique that enhances the optical absorptivity of metal powders used in 3D printing. The approach, which involves creating nanoscale surface features on metal powders, promises to improve the efficiency and quality of printed metal parts.

Using peptides and a snippet of the large molecules in plastics, scientists at Northwestern University have developed materials made of tiny, flexible nano-sized ribbons that can be charged just like a battery to store energy or record digital information. Highly energy efficient, biocompatible and made from sustainable materials, the systems could give rise to new types of ultralight electronic devices while reducing the environmental impact of electronic manufacturing and disposal. "This is a wholly new concept in materials science and soft materials research," said Samuel I.

Researchers from North Carolina State University and the U.S. Department of Energy’s Brookhaven National Laboratory have developed and demonstrated a technique that allows them to engineer a class of materials called layered hybrid perovskites down to the atomic level, which dictates precisely how the materials convert electrical charge into light. Layered hybrid perovskites can be laid down as thin films consisting of multiple sheets of perovskite and organic spacer layers.

A nanocrystalline material is made up of many tiny crystals, but as they grow, the nanocrystalline material can weaken. Researchers from Lehigh University, Johns Hopkins University, George Mason University, the University of Tennessee, Knoxville, and the U.S. Department of Energy’s Lawrence Berkeley National Laboratory and Sandia National Laboratories have discovered that the key to maintaining the stability of nanocrystalline materials at high temperatures lies in triple junctions – corners where three of these nanocrystals meet.