Argonne National Laboratory

Science Highlights

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Molecular model of stanene, a softer and consequently more rippled version of 2D tin than its analogs graphene and silicene. (Image by Mathew Cherukara, Badri Narayanan and Subramanian Sankaranarayanan/Argonne National Laboratory.)
Machine Learning Enables Predictive Modeling of 2-D Materials

Machine learning (ML) techniques have contributed towards development of the first atomic level model to accurately predict the thermal properties of stanene, a 2-D atomic sheet of tin.

December 9, 2016
Gary Wiederrecht, group leader and senior nanoscientist at Argonne’s Center for Nanoscale Materials, has received fellowship within the American Physical Society. (Argonne National Laboratory)
Argonne nanoscientist honored as fellow of the American Physical Society

Gary Wiederrecht, a senior nanoscientist at Argonne National Laboratory, has been elected a fellow of the American Physical Society.

November 4, 2016
Atomic-resolution striped undulations in borophene on a silver(111) surface via UHV scanning tunneling microscopy. Image courtesy of the American Chemical Society.
Nanoscale Undulations in Borophene on Silver Surfaces

Two-dimensional (2D) materials tend to be mechanically flexible yet planar, especially when adhered on metal substrates.

October 5, 2016
Water can serve a previously undiscovered role to help micelles spontaneously form long fibers. Molecular dynamics simulations highlight the transition of a peptide amphiphile (from C16-AHL3K3-CO2H molecules) assembly from micelles to fibers within microseconds. Water becomes more ordered with fiber formation. (Image courtesy of Robert Horn/Argonne National Laboratory.)
Drop-by-Drop: water helps assembly of biofibers that could capture sunlight

Simulations reveal water’s role in driving the self-assembly of peptide amphiphiles from monomers to micelles to fibers. Dual computational and experimental results provide a basis for designing new peptide materials capable of exhibiting light harvesting properties. Such artificial systems have potential in photochemical reactions and solar fuels.

October 4, 2016
A magnetic charge ice with nanoscale magnets arranged in a two-dimensional lattice. Each nanomagnet produces a pair of magnetic charges, one positive (red ball on the north pole) and one negative (blue ball on the south pole). The magnetic flux lines (white) point from positive charges to negative charges. (Image credit: Yonglei Wang and Zhili Xiao)
Rewritable Artificial Magnetic Charge Ice

An artificial magnetic charge structure with tunable long-range ordering to achieve the elusive ground state of a magnetic spin-ice structure was achieved. Manipulation of local magnetic charge states for write-read-erase multi-functionality at room temperature was demonstrated.

June 17, 2016
A patchwork map of lattices in a butterfly wing with slightly different orientations (colors added to illustrate the domains). This structure, and the irregularities along the edges where they meet, help create the “sparkle” of the wings. Image courtesy Ian McNulty/Science.
Butterfly Effects: X-rays reveal the photonic crystals in butterfly wings that create color

CNM scientists in collaboration with others used X-rays at the APS to discover what creates one butterfly effect: how the microscopic structures on the insect’s wings reflect light to appear as brilliant colors to the eye. The results may help researchers mimic the effect for reflective coatings, fiber optics or other applications.

June 17, 2016
Researchers from Argonne National Laboratory developed a first-principles-based, variable-charge force field that has shown to accurately predict bulk and nanoscale structural and thermodynamic properties of IrO2. Catalytic properties pertaining to the oxygen reduction reaction, which drives water-splitting for the production of hydrogen fuel, were found to depend on the coordination and charge transfer at the IrO2 nanocluster surface. (Image courtesy of Maria Chan, Argonne National Laboratory)
More accurate predictions for harvesting hydrogen with iridium oxide nanoparticles

Researchers from Argonne National Laboratory developed a first-principles-based, variable-charge force field that has shown to accurately predict bulk and nanoscale structural and thermodynamic properties of IrO2.

May 3, 2016
Molecular model, overlaying rectification ratio map, and current-voltage statistics “I(V)” of a pentacene/C60 heterojunction (top) and a C60 monolayer (bottom) on Cu(111).
Large rectification in molecular heterojunctions

C60 and pentacene self-assemble on a copper surface into stacked molecular heterojunctions which reveal robust diode-like behavior with rectification ratios (RR) >1000. Most organic systems have RRs <100. The new bilayer system has a novel mechanism, the RR >1000 is a lower bound, and the design is not yet optimized. Using this design, large rectification at metallic electrodes may be engineered by adding a ~2 nm-thick molecular layer for potential use in organic optoelectronics and photovoltaics.

April 19, 2016
On the left, a schematic shows the experimental setup for measuring spin dynamics in a sample of YIG. On the right, a Brillouin light scattering map of a micro-sized bar of YIG excited via an electrical current through a platinum overlayer reveals a strong spin-wave localization in the center of the sample known as a “bullet.” The color red indicates a high-spin wave intensity and the color blue indicates an absence of spin waves. (Image provided by M. Benjamin Jungfleisch)
Could the future of low-power computing be magnetism?

Researchers at the U.S. Department of Energy's (DOE's) Argonne National Laboratory have made two recent advances in the field of spin-wave logic, or the potential use of magnetic spins to transmit and manipulate data.

February 15, 2016
AC-TEM image of an individual Pt catalyst nanoparticle. The distances labeled 1 and 2 blue are 2.4 Å and 2.8 Å resp. Overlaid on the image are two layers of cubic Pt (magenta and green dots). The cubic 3-dimensional structure of Pt as a model is shown at the upper right, displaying the location of the Pt atoms in the two layers (corresponding magenta and green colors).
Advantages of Microscopy Method for Imaging Nanocatalysts

In work with UOP-Honeywell, a comparison of advanced microscopy methods for imaging platinum (Pt) catalyst nanoparticles suggests the aberration-corrected transmission electron microscopy (AC-TEM) mode may be advantageous because of the less pronounced beam-induced structural changes that occur when imaging with a fine scanning TEM (STEM) probe.

February 11, 2016