Lifeboat Foundation: Safeguarding Humanity
Toggle light / dark theme

Blog

Category: materials – Page 61

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.

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.

The hidden superconducting state in NbSe₂: Shedding layers and gaining insights

Researchers have discovered an unexpected superconducting transition in extremely thin films of niobium diselenide (NbSe2). Publishing in Nature Communications, they found that when these films become thinner than six atomic layers, superconductivity no longer spreads evenly throughout the material, but instead becomes confined to its surface.

This discovery challenges previous assumptions and could have important implications for understanding and developing advanced quantum technologies.

Researchers at the Hebrew University of Jerusalem have made a surprising discovery about how superconductivity behaves in extremely thin materials. Superconductors are materials that allow electric current to flow without resistance, which makes them incredibly valuable for technology. Usually, the properties of superconductors change predictably when the materials become thinner; however, this study found something unexpected.

/* */