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A team of researchers has identified a unique phenomenon, a “skin effect,” in the nonlinear optical responses of antiferromagnetic materials. The research, published in Physical Review Letters, provides new insights into the properties of these materials and their potential applications in advanced technologies.

Nonlinear optical effects occur when light interacts with materials that lack inversion symmetry. It was previously thought that these effects were uniformly distributed throughout the material. However, the research team discovered that in antiferromagnets, the nonlinear optical response can be concentrated on the surfaces, similar to the “skin effect” seen in conductors, where currents flow primarily on the surface.

In this study, the team developed a self-designed computational method to investigate the nonlinear optical responses in antiferromagnets, using the bulk photovoltaic effect as a representative example. Their results showed that, while the global inversion symmetry was broken, the local inversion symmetry deep inside the antiferromagnet was almost untouched.

Imagine if we could take the energy of the sun, put it in a container, and use it to provide green, sustainable power for the world. Creating commercial fusion power plants would essentially make this idea a reality. However, there are several scientific challenges to overcome before we can successfully harness fusion power in this way.

Researchers from the U. S. Department of Energy (DOE) Ames National Laboratory and Iowa State University are leading efforts to overcome material challenges that could make commercial fusion power a reality. The research teams are part of a DOE Advanced Research Projects Agency-Energy (ARPA-E) program called Creating Hardened And Durable fusion first Wall Incorporating Centralized Knowledge (CHADWICK). They will investigate materials for the first wall of a fusion reactor. The first wall is the structure that surrounds the fusion reaction, so it bears the brunt of the extreme environment in the fusion reactor core.

ARPA-E recently selected 13 projects under the CHADWICK program. Of those 13, Ames Lab leads one of the projects and is collaborating alongside Iowa State on another project, which is led by Pacific Northwest National Laboratory (PNNL).

In the quest for ultra-precise timekeeping, scientists have turned to nuclear clocks. Unlike optical atomic clocks—which rely on electronic transitions—nuclear clocks utilize the energy transitions in the atom’s nucleus, which are less affected by outside forces, meaning this type of clock could potentially keep time more accurately than any previously existing technology.

However, building such a clock has posed major challenges—thorium-229, one of the isotopes used in nuclear clocks, is rare, radioactive, and extremely costly to acquire in the substantial quantities required for this purpose.

Reported in a study published in Nature, a team of researchers, led by JILA and NIST Fellow and University of Colorado Boulder Physics professor Jun Ye, in collaboration with Professor Eric Hudson’s team at UCLA’s Department of Physics and Astronomy, have found a way to make nuclear clocks a thousand times less radioactive and more cost-effective, thanks to a method creating thin films of thorium tetrafluoride (ThF₄).

MIT physicists have created a new and long-lasting magnetic state in a material, using only light.

In a study that appears in Nature, the researchers report using a terahertz laser —a light source that oscillates more than a trillion times per second—to directly stimulate atoms in an antiferromagnetic material. The laser’s oscillations are tuned to the natural vibrations among the material’s atoms, in a way that shifts the balance of atomic spins toward a new magnetic state.

The results provide a new way to control and switch antiferromagnetic materials, which are of interest for their potential to advance information processing and memory chip technology.

Atomic simulations deepen the mystery of how engineered materials known as refractory high-entropy alloys can suffer so little damage by radiation.

Refractory high-entropy alloys are materials made from multiple high-melting-point metals in roughly equal proportions. Those containing tungsten exhibit minimal changes in mechanical properties when exposed to continuous radiation and could be used to shield the crucial components of future nuclear reactors. Now Jesper Byggmästar and his colleagues at the University of Helsinki have performed atomic simulations that explore the uncertain origins of this radiation resistance [1]. The findings could help scientists design novel materials that are even more robust than these alloys in extreme environments.

The researchers studied a tungsten-based refractory high-entropy alloy using state-of-the-art simulations guided by machine learning. In particular, they modeled the main mechanism by which radiation can disrupt such an alloy’s atomic structure. In this mechanism, the incoming radiation causes one atom in the alloy to displace another atom, forming one or more structural defects. The team determined the threshold energy needed to induce such displacements and its dependence on the masses of the two involved atoms.

By measuring the melting temperature of iron under high transient pressure, researchers set a limit on the temperature at the boundary between the inner and outer cores.

A laser-driven electron accelerator delivers beams of 10-GeV electrons—an approach that could lead to cheaper, more compact alternatives to large-scale x-ray sources and particle accelerators.

Using dual lasers and an advanced gas injection system, researchers at the Berkeley Lab Laser Accelerator Center (BELLA) accelerated a high-quality electron beam to 10 billion electronvolts (10 GeV) over a distance of just 30 centimeters.

Laser-plasma accelerators have the potential to dramatically shrink the size and cost of particle accelerators, benefiting fields such as high-energy physics, medicine, and materials science. Key achievements from BELLA’s recent experiment include:

Scientists are developing nuclear clocks using thin films of thorium tetrafluoride, which could revolutionize precision timekeeping by being less radioactive and more cost-effective than previous models.

This new technology, pioneered by a collaborative research team, enables more accessible and scalable nuclear clocks that may soon move beyond laboratory settings into practical applications like telecommunications and navigation.

Breakthrough in Nuclear Clock Technology.