(2025) Evolution of Catalyst Material Nanostructures

Wisconsin MRSEC researchers investigated how metal ions of palladium and copper, stabilized in zeolites, rearrange when exposed to high temperatures or reactive environments. They used cutting-edge X-ray characterization to ‘see’ structural changes in real time. Metal ions rearrange when exposed to reactive environments and agglomerate into clusters over time, which no longer work as well. These clusters can be returned active catalysts through controlled high-temperature treatments. These insights inform the design of efficient catalysts for energy applications.

(2025) Quantum Mechanics of 2D Electron Solids

Researchers in the Wisconsin MRSEC have shown that bilayer electron crystals exhibit a variety of magnetic states depending on the distance between the two layers and the number of electrons in each layer. These state include ferromagnetic and antiferromagnetic arrangements of electron spins, as well as exotic states like the valence-bond solid and spin-nematic. These results establish bilayer crystals as a promising platform for studying quantum magnetism and provide guidance for experiments characterizing electron solids realized in 2D materials.

(2024) Integration of High-k STO with Novel GaN High Voltage Transistors

Wisconsin MRSEC researchers have designed and fabricated a new dual-gate 1200 V GaN based bidirectional transistor with good performance. However, performance is limited by failure of the electrically insulating layer, which is currently amorphous silicon nitride (SiN), a conventional material. In the next generation of devices, the team has replaced SiN with a crystalline strontium titanate membrane (SrTiO3) developed by MRSEC IRG 2. SrTiO3 is a much better insulator, so the team expects record performance in ongoing device testing.

(2021) Controlling Waves with 3D Printed Materials

Materials with a repetitive pattern the same size as the wavelength of a wave can be used to control the wave, causing it to bend, perfectly reflect or transmit, or even turn around corners. Where different patterns meet, even more exotic behavior occurs, including making highways for light or sound that only travel in one direction or where the waves cannot be dissipated. Synthesizing such materials is a major challenge, which  Wisconsin MRSEC researchers have met by adapting a family of 3D printing techniques.

(2020) Energy Transfer Inside of a Topological Photonic Materials

The Wisconsin MRSEC has shown that molecules inside in a type of topological photonic material called a Weyl crystal can exchange energy over much larger distances. The intricate twisting structure of the material uses light to connect one molecule to others much farther away. Developing photonic Weyl crystals may contribute to more efficient LEDs and solar cells and improve molecular sensors.

(2020) Machine Learning Algorithms

The Wisconsin MRSEC has developed machine learning techniques that enable the design of new toxin sensors using liquid crystal droplets that respond to the presence of different bacterial toxins and at extremely low concentrations by changing shape and appearance. Machine learning enables computers to automatically analyze the droplet responses to measure toxin concentration and type automatically at high accuracy. More generally, these results demonstrate that the machine learning approach can quickly extract valuable information from complex datasets.

(2019) Design Rules for Soft Materials with Integrated Natural and Synthetic Building Blocks

Bacteria communicate via molecular signals that they produce in high concentrations. Bacterial communication promotes the formation of biofilms that can be harmful to humans and costly to industry. We have shown that collections of individual bacterial signaling molecules interact in water to form soft materials (“self-assemble”) with spherical, layered, or cylindrical structures. Simulation images showing the formation of a spherical structure (“micelle”) are shown with corresponding experimental images.