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Record-breaking material emits infrared light better than it absorbs it, without violating the laws of physics

New results published in the journal Physical Review Letters detail how a specially designed metamaterial was able to tip the normally equal balance between thermal absorption and emission, enabling the material to better emit infrared light than absorb it.

At first glance, these findings appear to violate Kirchhoff’s law of , which states that—under specific conditions—an object will absorb (absorptivity) in one direction and emit it (emissivity) with equal intensity in another, a phenomenon known as reciprocity.

Over the past decade, however, scientists have begun exploring theoretical designs that, under the right conditions, could allow materials to break reciprocity. Understanding how a material absorbs and emits infrared light (heat) is central to many fields of science and engineering. Controlling how a material absorbs and emits infrared light could pave the way for advances in harvesting, thermal cloaking devices, and other technologies.

TaIrTe₄ photodetectors show promise for highly sensitive room-temperature THz sensing

Terahertz radiation (THz), electromagnetic radiation with frequencies ranging between 0.1 and 10 THz, could be leveraged to develop various new technologies, including imaging and communication systems. So far, however, a lack of fast and sensitive detectors that can detect radiation across a wide range of frequencies has limited the development of these THz-sensing technologies.

In a recent paper published in Nature Electronics, researchers at the University of Wisconsin-Madison, the University of Tennessee and other institutes have introduced new photodetectors made of tantalum iridium telluride (TaIrTe₄), a 2D-correlated topological semimetal that exhibits advantageous properties. Most notably, this material exhibits a strong nonlinear Hall effect, a physical effect that entails a transverse voltage in the absence of an external magnetic field, which is nonlinearly proportional to an applied electric field or current.

“THz technology is critical in and biomedical sensing because its frequency resonates with low-energy collective excitations in quantum materials and molecular vibrations in biological matters,” Jun Xiao, senior author of the paper, told Phys.org.

Quantum machine learning improves semiconductor manufacturing for first time

Semiconductor processing is notoriously challenging. It is one of the most intricate feats of modern engineering due to the extreme precision required and the hundreds of steps involved, such as etching and layering, to make even a single chip.

Uncertainty—not just social context—drives brain activity when we ‘read the minds’ of others, psychologists find

Imagine you are about to confront a friend about a hurtful comment she made and are trying to predict her response. Depending on what you know about your friend, you might infer that she will understand where you’re coming from and apologize, get defensive, or respond with criticism of you.

This process of trying to predict other people’s beliefs, intentions, and emotions is known as mentalizing, and the dorsal medial prefrontal cortex (DMPFC) is one of the key brain regions that make up what is known as the “mentalizing network.” Studies have shown that the network is more engaged during mentalizing than when people make other kinds of inferences, such as about objects—like the comfort of a chair—or human physical traits.

But new research from psychologists at the University of Pennsylvania challenges the interpretation of these findings by highlighting a confounding variable in DMPFC activation: uncertainty.

ReSURF: Stretchable, self-healing water quality sensor enables ultrafast surveillance

Clean, safe water is vital for human health and well-being. It also plays a critical role in our food security, supports high-tech industries, and enables sustainable urbanization. However, detecting contamination quickly and accurately remains a major challenge in many parts of the world.

A new device developed by researchers at the National University of Singapore (NUS) has the potential to significantly advance water quality monitoring and management.

Taking inspiration from the biological function of the oily protective layer found on , a team of researchers led by Associate Professor Benjamin Tee from the Department of Materials Science and Engineering in the College of Design and Engineering at NUS translated this concept into a versatile material, named ReSURF, capable of spontaneously forming a water-repellent interface.

Magnetism recharged: A new method for restoring magnetism in thin films

Modern low-power solutions to computer memory rely heavily on the manipulation of the magnetic properties of materials. Understanding the influence of the chemical properties of these materials on their magnetization ability is of key importance in developing the field.

A study published in Applied Physics Letters, led by researchers from SANKEN at The University of Osaka, has revealed a technique for recovering magnetism in a degraded spintronics device. This method can be applied to improve the robustness of next-generation semiconductor memory.

Spintronics exploits the spin (and charge) of electrons to process and store memory, and this is achieved practically by stacking layers of thin material films that behave differently under the influence of a magnetic field.

What is the optimal setting for your air conditioner? We asked a physics professor

Ahh, summer, a time of vacations at the beach or mountains—and sky-high electricity bills as your air conditioner labors against the heat and humidity.

But what is the optimal temperature setting for your air conditioner?

And how does your body adapt to heat?

Northeastern University’s Stefan Kautsch, a teaching professor in physics, explains and how the concepts he discusses in the classroom can also help humans survive sweltering temperatures.

Unveiling hedgehog topological defects in three dimensional glasses

I’ve always been fascinated by how materials break down, especially glasses and polymers that don’t have a regular crystal structure. Unlike crystals, where we understand plasticity through things like dislocations, amorphous materials like glasses are messier. There’s no neat lattice to analyze, so figuring out where and how they deform under stress is a big open question.

In two dimensions, researchers, including my research group and myself, have started using a topological approach—looking at vortex-like patterns in how atoms move or vibrate—to identify weak spots in glasses. This also included slicing 3D glasses to find in the two-dimensional slices. That got me wondering: Could we do something similar in three dimensions, and, crucially, without having to slice the into 2D layers?

In this work published in Nature Communications, together with my postdoc Dr. Arabinda Bera, who performed the analysis, and with my longtime collaborator Prof. Matteo Baggioli, we show that we can. We use a kind of topological defect called a hedgehog, which is a point-like distortion in a vector field—like when tiny arrows in space all point outward or inward, just like the spines of a hedgehog. These kinds of defects are well-known in soft matter physics, particularly in liquid crystals, but we hadn’t seen them applied to 3D amorphous solids before.

Understanding the impact of radiation on silicon carbide devices for space applications

The first results of the ETH Zurich and ANSTO collaboration focused on silicon carbide (SiC) devices have been reported in two publications.

Dr. Corinna Martinella, formerly a senior scientist at ETH Zurich, said in a LinkedIn post that the research advances an understanding of the basic mechanisms of damage in SiC power devices exposed to .

An article in IEEE Transactions on Nuclear Science describes the testing of how commercial (SiC) power devices, including MOSFETs and Junction Barrier Schottky (JBS) diodes, respond to space-like radiation at a .

Puzzling Astronomers: Keck Observatory Detects Unexpected Signals From Nearby Star

Astronomers at the W. M. Keck Observatory on Maunakea, Hawaiʻi Island have detected unexpected signals from a nearby star, revealing insights that challenge current ideas about stellar behavior.

Using the Keck Planet Finder (KPF), the observatory’s most advanced instrument, the team measured oscillations within the star, subtle vibrations once thought undetectable. The results, published in The Astrophysical Journal.