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Category: materials – Page 22

A 32-bit RISC-V processor made using molybdenum disulfide instead of silicon

A team of engineers at Fudan University has successfully designed, built and run a 32-bit RISC-V microprocessor that uses molybdenum disulfide instead of silicon as its semiconductor component. Their paper is published in the journal Nature.

Most microprocessors are made using the semiconductor silicon, which has worked out well for several decades. But as researchers attempt to make processors ever smaller, they have run into a dead end with silicon—they cannot make it any thinner. Instead, many researchers have turned to 2D materials such as graphene, but this is challenging because it is a conductor, not a semiconductor.

In this new study, the research team used a nearly 2D semiconducting material, single-molecule sheets of molybdenum disulfide. These sheets are not truly 2D because they bond at an angle, resulting in a slightly zigzag surface. To make a processor out of them, they put them on a sapphire substrate.

With affordable materials, researchers pull carbon directly from the air using changes in humidity

Researchers at Northwestern University have expanded the potential of carbon capture technology that plucks CO2 directly from the air by demonstrating that there are multiple suitable and abundant materials that can facilitate direct air capture.

In a paper titled “Platform materials for moisture-swing carbon capture” published in the journal Environmental Science & Technology, the researchers present new, lower-cost materials to facilitate moisture-swing to catch and then release CO2 depending on the local air’s moisture content, calling it “one of the most promising approaches for CO2 capture.”

Atmospheric CO2 continues to increase and, despite considerable worldwide efforts to cut down on carbon waste, is expected to rise more in coming decades.

A new wave in ultrafast magnetic control

Researchers at the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) have developed an innovative method to study ultrafast magnetism in materials. They have shown the generation and application of magnetic field steps, in which a magnetic field is turned on in a matter of picoseconds.

The work has been published in Nature Photonics.

Magnetic fields are fundamental to controlling the magnetization of materials. Under static or slowly varying conditions, a material’s magnetization aligns with the external field like a compass needle. However, entirely new magnetization dynamics emerge when magnetic fields change on timescales—faster than the material’s response time.

Enhancing light control with complex frequency excitations

Researchers at the Advanced Science Research Center at the CUNY Graduate Center (CUNY ASRC) and at Florida International University report in the journal Science their insights on the emerging field of complex frequency excitations, a recently introduced scheme to control light, sound and other wave phenomena beyond conventional limits.

Based on this approach, they outline opportunities that advance fundamental understanding of wave-matter interactions and usher wave-based technologies into a new era.

In conventional light-wave-and sound-wave-based systems such as wireless cell phone technologies, microscopes, speakers and earphones, control over wave phenomena is limited by constraints, which stem from the fundamental properties of the materials used in these technologies.

Superconducting Surprise: Strange Behavior in Ultra-Thin Materials

A team of physicists uncovered a strange twist in how superconductors behave when they’re reduced to just a few atomic layers. Using powerful magnetic imaging, they found that superconductivity in ultra-thin materials doesn’t follow the usual rules – it becomes surface-based rather than distribut

Supersonic speed limit for strong metal bonding revealed

Faster isn’t always better when it comes to high-speed materials science, according to new Cornell research showing that tiny metal particles bond best at a precise supersonic speed.

In industrial processes like cold spray coating and , tiny metal particles travel at extreme speeds and slam into a surface with such force that they fuse together, forming strong metallic bonds. This rapid, high-energy collision builds up layers of material, creating durable, high-performance components. Understanding how and why these bonds form, and sometimes fail, can help optimize manufacturing techniques and lead to stronger materials.

In a study published March 31 in the Proceedings of the National Academy of Sciences, Cornell scientists launched , each about 20 micrometers in diameter, onto an aluminum surface at speeds of up to 1,337 meters per second—well beyond the speed of sound—and used high-speed cameras to record the impacts.

Highly twisted metamaterial rods store large amounts of energy

An international research team coordinated at KIT (Karlsruhe Institute of Technology) has developed mechanical metamaterials with a high elastic energy density. Highly twisted rods that deform helically provide these metamaterials with a high stiffness and enable them to absorb and release large amounts of elastic energy. The researchers conducted simple compression experiments to confirm the initial theoretical results. Their findings have been published in the journal Nature.

Storage of mechanical energy is required for many technologies, including springs for absorbing energy, buffers for mechanical energy storage, or flexible structures in robotics or energy-efficient machines. Kinetic energy, i.e., motion energy or the corresponding mechanical work, is converted into elastic energy in such a way that it can be fully released again when required.

The key characteristic here is enthalpy—the energy density that can be stored in and recovered from an element of the material. Peter Gumbsch, Professor for at KIT’s Institute for Applied Materials (IAM), explains that achieving the highest possible enthalpy is challenging: “The difficulty is to combine conflicting properties: high stiffness, and large recoverable strain.”

Researchers propose a simple magnetic switch using altermagnets

Controlling magnetism in a device is not easy; unusually large magnetic fields or lots of electricity are needed, which are bulky, slow, expensive and/or waste energy. But that looks soon to change, thanks to the recent discovery of altermagnets. Now scientists are putting forth ideas for efficient switches to manage magnetism in devices.

Magnetism has traditionally come in two varieties: ferromagnetism and antiferromagnetism, based on the alignment (or not) of in a material. Early last year, physicists announced experimental evidence for a third variety of magnetism: altermagnetism, a different combination of spins and crystal symmetries. Researchers are now learning how to tune altermagnets, bringing science closer towards practical applications.

We’re all familiar with ferromagnetism (FM), like a refrigerator magnet or compass needle, where magnetic moments in atoms lined up in parallel in a crystal. A second class was added about a hundred years ago called antiferromagnetism (AFM), where magnetic moments in a crystal align regularly in alternate directions on differing sublattices, so the crystal has no net magnetization, but usually does at low temperatures.

Rare quantum state spotted, thanks to thermopower signals in graphene

Such findings wouldn’t have been possible using the traditional resistivity approach. “We demonstrate that the magneto-thermopower detection of fractional quantum Hall states is more sensitive than resistivity measurements,” the researchers note.

“Overall, our findings reveal the unique capabilities of thermopower measurements, introducing a new platform for experimental and theoretical investigations of correlated and topological states in graphene systems, including moiré materials,” Ghahari concluded.

Hopefully, these findings will help us realize the true potential of the FQH effect. However, whether the same approach could be used to detect other exotic quantum states remains to be explored through further research.