ADVANCED MATERIALS & PROCESSES | NOVEMBER/DECEMBER 2025 13 ADDING WRINKLES TO 2D MATERIALS Materials scientists at Rice University, Houston, discovered that small creases in 2D materials can control electron spin with extreme precision, a finding that may speed development of ultracompact, energy-efficient electronic devices. It is believed that computing with spin could overcome the limitations of current silicon-based technology, reducing the energy footprint of devices and data centers. To combat the information decay typical with spin, the researchers found that bending atomically thin layers of materials like molybdenum ditelluride creates a unique spin texture called persistent spin helix (PSH), which can preserve spin state even in scattering collisions. The team hypothesized that wrinkles in 2D materials could be a way to control electron spin states: When a 2D material is bent, the top side of the sheet stretches while the bottom gets compressed. This uneven strain causes positive and negative charges to shift slightly relative to one another, producing an internal electric field called flexoelectric polarization. “Undulations are common in 2D materials, appearing as wrinkles or self-sustained hairpin-like loops when folded—creating regions with extremely high curvature,” says researcher Sunny Gupta. “We demonstrate that in such hairpin folds in molybdenum ditelluride, PSH states can achieve a spin-precession length of about 1 nanometer— the shortest reported to date.” A short precession length means spintronic devices can be much more compact. “Here we showed that not only do macroscopic changes in the geometry or shape of 2D materials have an impact on the deep quantum-relativistic interaction between electron spin and nuclei, but also that this effect can be harnessed to create exotic spin textures for novel spintronics,” added Gupta. rice.edu. SILVER NANOWIRE FILM HELPS INFRARED CAMERAS Researchers at NYU Tandon School of Engineering developed a transparent electrode made from embedding tiny silver wires into a transparent plastic matrix that can be easily deposited on top of conventional infrared detectors. “We’ve developed a material that solves a fundamental problem NANOTECHNOLOGY Graphical depiction of electron spins in a bent 2D material, which exhibits the persistent spin helix structure. Courtesy of Sunny Gupta. that has been limiting infrared detector design,” says Ayaskanta Sahu, associate professor. “Our transparent electrode material works well across the infrared spectrum, giving engineers more flexibility in how they build these devices.” The team tested their material by building it into infrared cameras that use colloidal quantum dots as the light-responsive material. For this study, the scientists used tiny clusters of mercury telluride, a type of quantum dot that responds to various wavelengths of infrared light. Their new approach represents a significant improvement over existing methods that rely on expensive materials like indium tin oxide or thin metal films, which either lose transparency in longer infrared wavelengths or suffer from poor electrical properties and must be rigid. Measuring 120 nm in diameter and 10-30 µm in length, the silver nanowires form conductive networks even at relatively low concentrations. When embedded in the PVA matrix, they form a silvery conductive ink that can be sprayed or spun onto infrared detectors as stable and flexible films that could even be manufactured at the low temperatures needed for quantum dot processing. engineering.nyu.edu. Scientists at Lawrence Livermore National Laboratory developed an electrically controlled smart window that can cut near-infrared light transmission by almost 50%. Their method relies on vertically aligned carbon nanotubes. llnl.gov, doi.org/10.1021/ acs.nanolett.5c00059. BRIEF Scanning electron microscopy of nanowires reveals areas of transparency and overlapping nanowires for electron transport. Courtesy of Håvard Mølnås.
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