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Category: materials – Page 2

Framework unifies the classical and quantum Mpemba effects

Physicists have developed a new theoretical framework which unifies a wide array of seemingly unrelated “Mpemba effects”: counterintuitive cases where systems driven further from equilibrium relax faster than those closer to it. Reporting their results in Physical Review X, researchers led by John Goold at Trinity College Dublin show that both classical and quantum versions of the effect can be understood using the same underlying logic—resolving a long-standing conceptual puzzle.

In 1963, 13-year-old Tanzanian student Erasto Mpemba noticed that when he placed an ice cream mixture in the freezer while it was still hot, it froze faster than the other, initially cooler mixtures in the freezer. His observation was later confirmed in 1969 through a study involving Mpemba, together with physicist Denis Osborne.

Since then, effects analogous to the Mpemba effect have been observed in transitions ranging from crystallizing polymers to transitions in magnetic materials. Yet despite close experimental scrutiny, the mechanisms underlying the effect remained elusive.

Scientists Say Washing Dishes With a Sponge Has a Concerning Side Effect

Kitchen sponges shed microplastics, but water use drives most environmental harm. Real-world and lab data show reducing water consumption has the greatest impact. Kitchen sponges may look harmless, but each scrub can release tiny plastic fragments that slip unnoticed down the drain. These micropl

Holographic storage approach packs more data into the same space by encoding three properties of light

Researchers have developed a holographic data storage approach that stores and retrieves information in three dimensions by combining three properties of light—amplitude, phase and polarization. By allowing more data to be stored in the same space, the new approach could help advance efforts to meet the growing global demand for data storage.

Holographic data storage uses laser light to store digital information inside a material. Instead of recording data only on a surface, like a hard drive or optical disk, it stores many overlapping light patterns throughout the volume of the material, allowing much higher storage density and faster data transmission.

“In conventional holographic data storage, data encoding typically uses one light dimension such as amplitude or phase alone, or, at most, combines two of these dimensions,” said research team leader Xiaodi Tan from Fujian Normal University in China.

XRISM clocks hot wind of galaxy M82 at 2 million mph

For the first time, astronomers have directly measured the speed of superheated gas billowing from a cauldron of stellar activity at the heart of M82, a nearby galaxy undergoing an extraordinary burst of star formation. The material is moving more than 2 million miles (over 3 million kilometers) per hour and appears to be the primary force driving a cooler, well-studied, galaxy-scale wind.

Researchers made the calculations using data from the Resolve instrument aboard the XRISM (X-ray Imaging and Spectroscopy Mission) spacecraft.

“The classic model of starburst galaxies like M82 suggests that shock waves from star formation and supernovae near the center heat gas, kick-starting a powerful wind,” said Erin Boettcher, an astrophysicist at the University of Maryland, College Park and NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

Finding order in disorder: New mechanism amplifies transverse electron transport

For decades, it has been widely believed that electrons move most efficiently in materials that are clean and highly ordered. Much like water flowing more easily through a smooth pipe, conventional wisdom has held that electrical transport improves as a material’s internal structure becomes more perfectly arranged. However, a recent study shows that the opposite can also be true. A research team at POSTECH in South Korea has discovered that engineered disorder can actually enhance electron transport.

The work was conducted by Prof. Hyungyu Jin of the Department of Mechanical Engineering at POSTECH (Pohang University of Science and Technology), Dr. Sang Jun Park (currently a postdoctoral researcher at the National Institute for Materials Science, NIMS, Japan), Prof. Hyun-Woo Lee of the Department of Physics at POSTECH, and Ph.D. student Hojun Lee.

Their findings are published in Physical Review Letters.

Magnets turn random snapping in soft metamaterials into repeatable sequences

Cutting patterns into elastic materials allows you to unfold those materials into new shapes, and researchers have now demonstrated the ability to control the sequence in which that unfolding happens by magnetizing the materials. The work represents a fundamental advance in our understanding of metamaterial behavior and has also demonstrated its utility in applications focused on absorbing kinetic energy.

The paper, “Magnetic coupling transforms random snapping into ordered sequences in soft metamaterials,” is published in the journal Science Advances.

“If you cut a T-pattern into a polymer sheet, you’ve created a metamaterial, because you’ve changed the properties of the material,” says Haoze Sun, first author of a paper on the work and a Ph.D. student at North Carolina State University. “If you pull the metamaterial sheet, all the cuts essentially pop open at once. These openings create a mesh-like pattern and extend the length of the sheet.

New light trap design supercharges atom-thin semiconductors

Scientists have found a clever way to supercharge ultra-thin semiconductors by reshaping the space beneath them rather than altering the material itself. By placing a single-atom-thick layer of tungsten disulfide over tiny air cavities carved into a crystal, they created miniature “light traps” that dramatically boost brightness and optical effects—up to 20 times stronger emission and 25 times stronger nonlinear signals. These hollow structures, called Mie voids, concentrate light exactly where the material sits, overcoming a major limitation of atomically thin devices.

A spinel crystal structure exhibits unusual, pressure-induced superconductivity

Superconductors are materials that conduct electricity with an electrical resistance of zero. Superconductivity is generally observed when materials are cooled down to extremely low temperatures. In some cases, however, like in so-called high-temperature superconductors, this property emerges at higher temperatures.

Researchers at the Center for High Pressure Science & Technology Advanced Research, Chinese Academy of Sciences and other institutes recently observed pressure-induced superconductivity in CuIr2S4, a spinel that typically becomes an insulator when cooled below about 230 K, meaning that electricity can no longer flow through it.

Their paper, published in Physical Review Letters, shows that progressively tuning this material’s crystal structure using pressure prompts the emergence of two distinct superconducting phases, dubbed SC-I and SC-II, with a maximum transition temperature of 18.2 K.

A Hall ‘rectenna’ can detect signals over a 100 GHz frequency range

Many current wireless communication, imaging and sensing technologies rely on components that convert oscillating electric and magnetic fields (i.e., electromagnetic waves) into electrical signals. Some of the most used components are so-called p-n diodes, semiconducting devices that combine two types of materials with distinct electrical properties.

In conventional diode designs, the conversion of electromagnetic waves into electrical signals relies on the nonlinear transport of electrons. This means that the electric current in the devices does not change proportionally with the voltage applied, which allows them to rectify signals (i.e., convert alternating current into direct current) and combine signals with different frequencies.

A key limitation of traditional diodes is that thermal effects introduce noise, causing electrons to move randomly and making weak signals harder to detect. Moreover, electrons typically take a finite time to travel across the device, also known as the transit time, which limits the performance of the diodes at very high frequencies.

Superconducting altermagnets could carry spin without energy loss

Researchers have proposed that a newly identified class of magnetic materials could extend the zero-resistance currents of superconductors to electron spins. Publishing their calculations in Physical Review X, Kyle Monkman and colleagues at the University of British Columbia propose how “altermagnets” could enable persistent spin currents to flow without dissipation. If confirmed experimentally, the effect could provide a powerful new platform for spintronics, where information is encoded in spin rather than electric charge.

The ability to transport spins over long distances is a central challenge in spintronics. In conventional metals and semiconductors, spin currents decay rapidly due to effects that randomize electron spins. One promising workaround has been superconducting spintronics, where dissipationless charge transport is combined with magnetic materials. However, these hybrid systems often suffer from intrinsic drawbacks, including stray magnetic fields that can interfere with nearby components, suppressing superconductivity.

First confirmed in 2024, altermagnets offer a potential way around these problems. Like antiferromagnets (where a magnetic dipole’s spin is always opposite to those of its neighbors), they have zero net magnetization, avoiding unwanted magnetic fields.

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