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Category: materials

Laser experiments push helium to record shock pressures

Deep inside gas giants like Jupiter and Saturn, hydrogen and helium coexist under pressures millions of times greater than Earth’s atmosphere. Under those conditions, helium may separate from hydrogen and influence a planet’s internal heat flow, structure and magnetic field. Understanding these processes and how these materials behave under extreme conditions is essential to building accurate models of planetary evolution.

New experimental results, published in Physical Review Research, reveal the behavior of helium at unprecedented pressures. The research, conducted by scientists at Lawrence Livermore National Laboratory (LLNL), the University of California, Berkeley, the French Commissariat à l’Énergie Atomique et aux Energies Alternatives (CEA) and the University of Rochester’s Laboratory for Laser Energetics (LLE), shows that helium behaves differently from what most broad-range theoretical models predicted.

A magnetic field that kills superconductivity can also bring it back

Magnetic fields are generally known to destroy superconductivity in a material. However, in exceptional cases, they can lead to what is known as “re-entrant superconductivity”—where superconductivity disappears as expected, but then unexpectedly returns when the magnetic field is increased further.

This behavior is sometimes seen in bulk, three-dimensional materials, but now, in a study published in Science Advances, a team led by the RIKEN Center for Emergent Matter Science (CEMS) in Japan has seen the phenomenon in a very thin conducting layer at the boundary between two insulating oxide materials. Because oxide interfaces can be precisely engineered and controlled, the discovery provides a new platform for investigating unconventional forms of superconductivity and the quantum mechanisms that allow it to survive under unusual conditions.

Geometric anti-spring works near absolute zero, suppressing vibrations below 0.185 hertz

Physicists and instrument makers in Leiden have succeeded in optimizing a spring that almost completely filters out vibrations at temperatures near absolute zero. This breakthrough opens the door to a new generation of highly sensitive experiments. The research is published in the journal Measurement Science and Technology.

“Our new special spring reduces the disruptive vibrations down to 0.185 hertz, which is a major improvement,” says Ph.D. candidate Louw Feenstra. Instrument makers Kees van Oosten and Hugo van Bohemen designed and built the new instrument in their workshop and tested it in the lab together with Feenstra.

Today, many—if not all—modern physics experiments are based on extremely precise measurements. Such measurements are often carried out inside a cryostat, a device that cools materials to temperatures as close as possible to absolute zero (0 Kelvin equals −273.15°C). Until now, cryostats had one major drawback: Their cooling systems generate strong vibrations, particularly around 1 hertz—roughly one vibration per second. For sensitive experiments, this can seriously affect the results.

Interlayer self-doping could unlock room-temperature multiferroics in atom-thin materials

Multiferroics are materials that exhibit more than one prominent “ferroic” property, such as ferromagnetism and ferroelectricity. One of their most advantageous features is that they allow engineers to control their magnetic states with electric fields or vice versa, due to an effect known as magnetoelectric coupling.

Listening for quantum oscillations in the Kondo insulator ytterbium dodecaboride

Magnetic quantum oscillations have been unexpectedly observed in insulators, where freely moving charge carriers are not expected to exist. A joint study by researchers from Tokyo University of Science, The University of Tokyo and Kobe University investigated this puzzling behavior in the Kondo insulator YbB12 using ultrasound.

The findings are published in the journal Physical Review B.

While no oscillations were detected in the insulating state, clear signals emerged after the material became metallic, offering new insight into unusual quantum behavior in next-generation materials.

Scientists create optical skyrmions using a two-century-old light phenomenon

Nanyang Technological University, Singapore (NTU Singapore) scientists have used a classic optical phenomenon known as the Poisson spot to create stable patterns of light called optical skyrmions, which are tiny, swirling configurations in the properties of light—akin to the spikes of a hedgehog.

The team used a laser directed at a small circular disk instead of the complex and costly engineered materials commonly used to generate these skyrmions. This new method gives scientists a much simpler way to generate, study and adjust optical skyrmions.

Skyrmions are currently a hot scientific subject because they hold the potential to store information, paving the way for future data storage, communications and computing systems.

Broken time-reversal symmetry phase in kagome metals may establish conditions for superconductivity

Physicists have long suspected that a peculiar quantum state lurks inside a class of materials known as kagome metals, but proving its existence has been elusive. Now, a team led by Yeongkwan Kim at the Korea Advanced Institute of Science and Technology has performed experiments on a kagome metal that provide the strongest evidence yet for this exotic state.

Published in Nature Physics, the team’s results could shed new light on how these materials transition into superconductivity.

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