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Category: materials – Page 11

Narrow ultrasonic beam enables stable 3D levitation six times farther than before

Scientists have developed a new acoustic levitation technique using an ultrasonic beam capable of levitating and moving small objects in midair over distances of up to 40 cm (16 inches), six times farther than previously achieved using conventional methods. The study, carried out by a research team from the University of Tsukuba in Japan and the University of Bristol, was published in the journal Physical Review Letters.

Acoustic levitation is a technique that uses sound waves to suspend objects in midair without physical contact—meaning it has the potential to be beneficial for handling fragile materials, contamination-sensitive samples and hazardous substances.

Conventional acoustic levitation systems rely on sound waves generated within an enclosed space, but the new technique is the first time a single-sided design has demonstrated stable acoustic levitation in three dimensions.

High magnetic fields revive superconductivity in nickelates

Scientists from the National University of Singapore (NUS), in collaboration with Los Alamos National Laboratory in the United States, have uncovered that a class of nickel-based materials known as samarium (Sm)-based infinite-layer nickelates can regain their superconducting ability under strong magnetic fields. This behavior could open a promising pathway toward superconducting technologies that can operate under extreme magnetic conditions.

Superconductivity, the ability of certain materials to conduct electricity without resistance, is typically destroyed by strong magnetic fields. However, a research team led by Professor Ariando from the Department of Physics at NUS, working with scientists from Los Alamos National Laboratory, has shown that Sm-based infinite-layer nickelates defy this expectation.

In these nickelates, superconductivity is first suppressed at low magnetic fields of a few tesla, only to reappear as the field increases, persisting beyond 60 tesla (hundreds of thousands of times stronger than Earth’s magnetic field). This unusual behavior, known as reentrant superconductivity, has previously been observed only in materials with very low transition temperatures, limiting their practical relevance.

Researchers Solve Two Major Problems Holding Back SiC Electronics

A new bottom gate design takes advantage of the intrinsic properties of SiC.

For more than 20 years, silicon carbide – SiC – has been viewed as a promising material for electronics that must function in extreme environments. Yet despite years of research, that promise has rarely translated into practical devices. Researchers at Kyoto University are now trying to move the field beyond that barrier.

“We believe the lack of development is because the research community has been trying to apply silicon-era thinking to a fundamentally different material,” says first author Mitsuaki Kaneko.

The superconducting gap of an ultrathin nickelate defies expectations

Superconductors are materials that carry electrical current with zero resistance below a specific critical temperature. In conventional superconductors, the transition to superconductivity generally occurs at very low temperatures.

Some unconventional superconductors, however, enter their superconducting phase at comparatively higher critical temperatures. This could be advantageous for practical applications, as superconductivity at higher temperatures could reduce the need for complex and expensive cooling systems. However, these materials generally still require substantial cooling.

Researchers at Nanjing University, the University of Science and Technology of China, the Hong Kong Polytechnic University and other institutes in China recently investigated the electronic processes underpinning superconductivity in La₃Ni₂O₇, a nickelate that has exhibited superconductivity at temperatures of up to around 80 K (−193°C, −316°F) under very high pressure.

Physicists Discover Time Crystals Can Communicate Across a Semiconductor

Separate time crystals inside a semiconductor can “find” each other across surprising distances and lock into the same rhythm.

Researchers at TU Dortmund University demonstrated the effect using a semiconductor system in which electron and nuclear spins form continuous time crystals. Their latest experiments, published in Nature Communications, reveal that spatially separated oscillators can lock to the same frequency even when they begin with different rhythms.

The finding builds on the team’s earlier demonstration of an unusually robust continuous time crystal in a semiconductor. That system produced persistent electron-nuclear spin oscillations with coherence lasting for hours, giving the researchers a stable platform for exploring what happens when several time crystals occupy the same material.

Meteorite dust holds records of magnetism that may have helped form the sun

4.6 billion years ago, the solar system was little more than a giant ball of gas and dust. Over the next few million years, this “solar nebula” underwent a huge transformation, flattening into a disk of matter that then condensed to form the central sun and orbiting planets.

Scientists have assumed that the early solar system was shaped mainly through gravity. But a new study finds that magnetism also likely played a role.

MIT scientists have discovered records of ancient magnetism in the oldest samples of meteorites known today. The team analyzed microscopic grains embedded in a meteorite that was discovered in Antarctica in 2008. These grains, called calcium-aluminum-rich inclusions, or CAIs, originally formed during the solar system’s first 200,000 years, making the samples the oldest known solar system material.

Oxygen vacancies unlock fast lithium-ion transport in battery material

Lithium titanate (LTO, Li4Ti5O12) is a well-established battery material that in its pristine state is a poor conductor of lithium ions. It develops high ionic conductivity only during charging, when additional lithium ions and electrons are incorporated into the material.

Bernhard Gadermaier and Martin Wilkening from the Institute of Chemistry and Technology of Materials at TU Graz have taken an entirely different approach: They transformed pure, non-lithiated LTO in its original composition, Li4Ti5O12, into a significantly better ion conductor by deliberately introducing defects into the crystal lattice.

Specifically, they removed individual oxygen atoms, thereby creating oxygen vacancies that activate a previously blocked migration pathway for lithium ions. “This diffusion pathway is already pre-formed in the LTO structure but is only activated by the defect structure,” Wilkening explains.

Moving beyond passive RAG: How to implement active memory reconstruction for AI agents

To see how this works in practice, consider a concrete enterprise use case: a customer success agent that needs to answer, “Why was this customer promised a different renewal price, and should we honor it?”

The answer may require reconstructing a causal chain across a support conversation, a sales exception, a contract clause, a billing-system update, and a later internal note. Traditional similarity-based RAG might retrieve the most recent billing document or the most semantically similar support ticket, but fail to connect the causal chain.

With MRAgent’s active reconstruction, the agent can extract cues like the customer’s name, follow associative tags to the original support ticket, retrieve the sales exception, and link it to the billing update. It navigates these semantic relationships, prunes irrelevant branches, and iteratively stops once it has enough evidence to answer the query.

Hypersonic impact rapidly transforms diamond into graphite, revealing energy-absorbing mechanism

Rice University researchers have developed a way to stabilize diamond during high-temperature and low-pressure processing, creating a strong bulk composite and discovering that high-speed collisions can rapidly transform diamond into graphite. Their study is published in Materials Today.

Diamond is one of the hardest known materials, with high thermal conductivity, properties that make it valuable for technologies that operate under extreme conditions. The findings could help researchers design tougher materials for aerospace, defense and other demanding environments by showing how diamond changes and absorbs energy under extreme force.

“This was quite an exciting outcome as it is nearly impossible to sinter diamond at lower pressures, and this new process we have developed could lead to the large-scale manufacturing of diamond-based composites,” said Pulickel Ajayan, the lead author of the study and the Benjamin M. and Mary Greenwood Anderson Professor of Engineering.

Soft vibrations reveal warning signs before granular crystals yield

Sand, powders, and other collections of visible-sized grains are found throughout daily life, from food and pharmaceuticals to soils and industrial materials. When grains of similar size are arranged regularly, they can form a strong crystal-like solid. Yet what happens inside such an ordered structure immediately before it begins to break has remained unclear.

Researchers at the University of Osaka, Shimane University, and Kyoto Sangyo University have now theoretically identified an unusual pattern of vibrations that emerges just before a crystal made of regularly arranged grains yields. Many vibrational modes soften simultaneously along particular directions, while long-wavelength waves travel more slowly than shorter ones. The findings, published in Physical Review E, reveal a possible physical precursor to failure in highly ordered particulate materials.