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Category: materials

Glass cells of atoms offer a new path to smarter, cheaper sensors

More accurate navigation systems and improved wireless communications may not come from traditional electronics, but rather from atoms. Researchers at Penn State and the National Institute of Standards and Technology (NIST) have developed a new way to build tinier, smarter glass sensors filled with highly precise and stable atoms.

The team’s work, published this week (June 18) in Microsystems and Nanoengineering, centers on a manufacturable, silicon-free version of traditional bulky “vapor cells”—sealed chambers that contain cesium and rubidium atoms—that are commonly used in precision measurement systems, in a gas state. These atoms can act as highly precise sensors because, unlike manufactured components, atoms are fundamentally identical.

“Using atoms for sensing is advantageous because the physics of individual atoms is very well understood, and all the atoms are equal,” said Daniel Lopez, co-lead author of the paper, Liang Professor of Electrical Engineering and Computer Science at Penn State and director of the Nanofabrication Lab at the Materials Research Institute (MRI). “That gives you a level of precision that’s very hard to achieve with traditional microfabricated devices.”

Novel crystal strategy delivers near-perfect zero thermal expansion from 11 K to 893 K

Almost every material expands when heated. Well-known examples include railroad tracks and concrete roadways, which feature visible expansion gaps to accommodate this effect. However, thermal expansion poses a far more acute challenge for extremely precise technologies, such as lasers and semiconductor manufacturing equipment, where even minute dimensional changes can compromise precision.

Scientists have long sought to develop materials that maintain dimensional stability across a wide temperature range.

Now, a team led by Prof. Lin Zheshuai from the Technical Institute of Physics and Chemistry (TIPC) of the Chinese Academy of Sciences (CAS) has designed a material with an exceptionally broad zero-thermal-expansion temperature window.

Hope for spinal injuries as pigs walk again after experimental gel treatment for severed spinal cords

In humans and other mammals, spinal cord injuries can be devastating, leading to permanent loss of movement, sensation and bladder control. When severed axons (the long fibers that carry messages between nerve cells) cannot regrow, a dense scar forms, preventing nerve signals from passing the injury site.

But the situation is different for some primitive invertebrates, which can rapidly reconnect severed nerves by fusing them. Inspired by this natural phenomenon, scientists led by Michael Lebenstein-Gumovski at the Sklifosovsky Institute for Emergency Medicine in Russia report that they have successfully reconnected severed spinal cords in pigs, enabling them to walk again.

When a spinal cord is completely cut, the two severed ends naturally pull away from each other. In microscopic roundworms, for example, the nerve ends automatically find each other and fuse together. The researchers realized that to recreate a natural fusion process like this, they needed a material to fill the empty space and hold the two ends together.

Special Spin State Triggered by Curved Surface

The field of magnonics aims to take advantage of spin waves, which are waves of precessing spins that can propagate in certain magnetic materials. A spin wave containing many equally spaced frequencies—called a magnon frequency comb (MFC)—would be especially useful for information processing and magnetic-field detection. Unfortunately, generating such waves is complicated. Now Peng Yan and his colleagues at the University of Electronic Science and Technology of China have shown theoretically that MFCs could be produced by simply creating a tiny bump in a thin magnetic layer [1].

Creating an MFC in a magnetic material usually entails creating an intricate pattern or “texture” of spin orientations in a small region—such as a spin vortex—and irradiating those spins with monochromatic microwaves. To avoid the complexities of spin textures, Yan and his colleagues propose introducing a bump in a few-nanometer-thick magnetic film. Previous research showed that material curvature can affect spin waves, for example, by modifying the frequency–wavelength relationship.

Exploiting another curvature effect, the theorists showed that a bump between 4 and 64 nm high can spontaneously create a set of spin waves that remain restricted to the bump region. Irradiating the bump with microwaves of a specific frequency then excites these waves and launches an MFC that travels away from the bump. Adjusting the height of the bump changes the spacing of the comb frequencies. Team member Hao Zhao says that in addition to possibly making MFCs more widely available, the work shows the potential for using geometry to manipulate spin waves in new ways.

Quantum waves reveal one-sided motion marking elusive critical states

Sound waves, light waves and other types of waves, generally spread freely through space and over time. In 1958, physicist Philip W. Anderson first described a phenomenon via which irregularities or other sources of disorder in materials would prevent waves from propagating freely, which is now known as Anderson localization.

In quantum systems, one can observe quantum states that are spread throughout a system (i.e., extended), confined to a small region (i.e., localized) or somewhere between the two (i.e., critical). Critical quantum states have so far proved to be very difficult to identify and study using Anderson’s localization theory.

Researchers at the International Quantum Academy and Southern University of Science and Technology in China recently set out to further explore critical quantum states in a quantum processor based on superconducting qubits.

Tiny water droplets transmutate aniline into pyridine in ambient and catalyst-free conditions

Aniline can now be transformed into pyridine without adding any catalysts, oxidants or toxic reagents. In a recent study published in the Journal of the American Chemical Society, researchers achieved skeletal editing, involving the reorganization of the carbon-nitrogen bonds within an aromatic ring, by turning an aqueous solution of aniline into a mist of microdroplets.

During its millisecond-long airborne lifespan, aniline underwent rapid molecular rearrangement, inserting nitrogen into the aromatic ring and forming pyridine, driven by the uniquely active air-water interface in microdroplets. The green, reagent-free reaction converted up to 80% of the starting material into the product under ambient conditions, eliminating the added energy cost often required to carry out such conversion reactions.

By testing droplets of different sizes, charges and acidity levels, researchers found that the reaction is boosted at the droplet’s interface, a zone that is rich in protons and highly polarized. The smaller the droplet, the larger its reactive surface area relative to its volume, and the better the reaction outcome.

Ultra-fast light-shaping technology could be ‘game-changer’ for future imaging

Scientists have developed a new type of “virtual” metasurface—capable of controlling light in ways traditional lenses and optics can’t—which they say is superior to the current approach, which relies on ultrathin engineered materials. The Nottingham Trent University team says the work will help fully optimize metasurface potential for a range of real-world applications and paves the way for a move from physical to virtual platforms in nanotechnology.

Metasurfaces are many times thinner than a human hair and can bend and focus light, change its color and steer it in different directions, meaning they can replace bulky optical elements in small devices such as lenses, mirrors and filters.

While they are powerful, however, the materials and dimensions of physical metasurfaces are fixed—once built, they can’t change their shape, which can limit how useful they are in real-world technologies.

Nearly isotropic superconducting property revealed in trilayer nickelate

A research team led by Prof. Zhang Jinglei from Hefei Institutes of Physical Science, Chinese Academy of Sciences, found that the trilayer nickelate La4Ni3O10-δ exhibits a nearly isotropic upper critical field under high pressure. This finding provides important experimental insight into the superconducting mechanism of nickel-based materials.

The study is published in Physical Review X.

Since the discovery of superconductivity with a transition temperature (Tc) approaching 80 K under high pressure in the bilayer Ruddlesden–Popper (RP) nickelate La3Ni2O7-δ, bulk superconductivity (Tc≈20 K) has also been verified in single crystals of the trilayer isostructural compound La4Ni3O10-δ under pressure. However, probing its properties remains technically demanding, as experiments must simultaneously achieve ultra-high pressure, strong magnetic fields and cryogenic temperatures.

Agentic AI bot helps scientists speak to robots, speeding up experiments

Researchers at the Department of Energy’s Pacific Northwest National Laboratory use a slew of autonomous robots to design and implement experiments. However, setting up an experiment on an autonomous lab robot is surprisingly slow. The effort requires a lengthy back-and-forth between a scientist and an engineer to design the experimental steps—a process that can take weeks.

To help researchers work more efficiently, a PNNL team developed a generative agentic AI that can quickly translate experimental goals into instructions for a laboratory robot. The translation agent, called AutoLabs, is currently designed to operate with Big Kahuna, an automated robot built by Unchained Labs that researchers use to study new and existing battery materials. The system can carry out multistep experimental workflows, including mixing, heating, stirring and filtering samples with minimal human intervention. By automating these processes, researchers can perform five to 10 times more experiments than would be practical by hand.

The team published a paper in Scientific Reports about AutoLabs, and the software is also available for other researchers to download on GitHub.

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