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Category: particle physics

Detecting the hidden magnetism of altermagnets

Altermagnets are a newly recognized class of antiferromagnets whose magnetic structure behaves very differently from what is found in conventional systems. In conventional antiferromagnets, the sublattices are linked by simple inversion or translation, resulting in spin-degenerate electronic bands. In altermagnets, however, they are connected by unconventional symmetries such as rotations or screw axes. This shift in symmetry breaks the spin degeneracy, allowing for spin-polarized electron currents even in the absence of net magnetization.

This unique property makes altermagnets exciting candidates for spintronic technologies, a field of electronics that utilizes the intrinsic spin of the electrons, rather than just their charge, to store and process information. As spins can flip or switch direction extremely quickly, materials that allow spin-dependent currents could enable faster and more energy-efficient electronic devices.

Ultracold atoms observed climbing a quantum staircase

For the first time, scientists have observed the iconic Shapiro steps, a staircase-like quantum effect, in ultracold atoms.

In a recent experiment, an alternating current was applied to a Josephson junction formed by atoms cooled to near absolute zero and separated by an extremely thin barrier of laser light. Remarkably, the atoms were able to cross this barrier collectively and without energy loss, behaving as if the barrier were transparent, thanks to quantum tunneling.

As the oscillating current flowed through the junction, the difference in chemical potential between the two sides did not change smoothly, but instead increased in discrete, evenly spaced steps, like climbing a quantum staircase. The height of each step is directly determined by the frequency of the applied current, and these step-like chemical potential differences are the atomic analog of Shapiro steps in conventional Josephson junctions.

Dark Matter Breakthrough: Physicists Crack “Big Bang Theory” Puzzle

A new theoretical study suggests fusion reactors could do more than generate energy, they might also produce particles linked to dark matter. Researchers at the University of Cincinnati say they have worked out, at least on paper, how fusion reactors could produce subatomic particles known as axi

Physicists Tighten the Net Around the Elusive Sterile Neutrino

High-precision measurements from the KATRIN experiment strongly limit the existence of light sterile neutrinos and narrow the search for new physics. Neutrinos are extremely difficult to detect, yet they are some of the most abundant matter particles in the Universe. The Standard Model includes t

Reversible spin splitting effect achieved in altermagnetic RuO₂ thin films

A research team affiliated with UNIST has made a advancement in controlling spin-based signals within a new magnetic material, paving the way for next-generation electronic devices. Their work demonstrates a method to reversibly switch the direction of spin-to-charge conversion, a key step toward ultra-fast, energy-efficient spintronic semiconductors that do not require complex setups or strong magnetic fields.

Led by Professor Jung-Woo Yoo from the Department of Materials Science and Engineering and Professor Changhee Sohn from the Department of Physics at UNIST, the team has experimentally shown that within the altermagnetic material ruthenium oxide (RuO₂), the process of converting spin currents into electrical signals can be precisely controlled and flipped at will.

This breakthrough is expected to accelerate the development of low-power devices capable of processing information more efficiently than current technologies. The study is published in the journal Nano Letters.

Raindrops form ‘sandballs’ as they roll downhill, contributing more to erosion than previously thought

What happens as a raindrop impacts bare soil has been fairly well-studied, but what happens to raindrops afterward is poorly understood. We know that the initial splash of raindrops on soil contributes to erosion, but a new study, published in the Proceedings of the National Academy of Sciences, finds that the journey of the raindrop downhill might have an even bigger impact on erosion than the initial splash.

Somewhere on the “Route de la Sorge” in Ecublens, Switzerland, members of the research team observed natural raindrops hitting the surface of a hillside and noticed that they collected particles of sand as they rolled downhill. This spurred the researchers to document the event with a camera and then take the idea to the lab.

In the lab, they constructed a 1.2 meter long bed covered with dry silicate sand and tilted at an angle of 30°. The lab conditions enabled the team to properly document the phenomenon by recording the evolution of the raindrops’ shapes as they rolled and take precise measurements of the relevant parameters. They found that each raindrop formed what they refer to as “sandballs” and that they took on differing shapes, depending on the conditions, and that the sandballs can move up to 10 times more soil than the initial splash alone.

Ultrafast fluorescence pulse technique enables imaging of individual trapped atoms

Researchers at the ArQuS Laboratory of the University of Trieste (Italy) and the National Institute of Optics of the Italian National Research Council (CNR-INO) have achieved the first imaging of individual trapped cold atoms in Italy, introducing techniques that push single-atom detection into new performance regimes.

By combining intense, microsecond-scale fluorescence pulses with fast re-cooling, the team demonstrated record-speed, low-loss imaging of individual ytterbium atoms—capturing clear single-atom signals in just a few microseconds while keeping more than 99.5% of the atoms trapped and immediately reusable.

This approach allows researchers to distinguish multiple atoms within a single optical tweezer without significant blurring, enabling precise onsite atom counting rather than the binary “zero-or-one” detection typical of existing methods. This capability is key for scaling neutral-atom quantum computers, advancing next-generation atomic clocks, and enhancing quantum simulators that probe complex many-body physics.

Rare Hall effect reveals design pathways for advanced spintronic materials

Scientists at Ames National Laboratory, in collaboration with Indranil Das’s group at the Saha Institute of Nuclear Physics (India), have found a surprising electronic feature in transitional metal-based compounds that could pave the way for a new class of spintronic materials for computing and memory technologies.

Spintronics, a field that harnesses the spin of electrons in addition to their charge, promises breakthroughs in technologies such as brain-like computers and memory devices that retain data without power.

The unexpected feature was found in Mn₂PdIn, a Heusler compound—a type of alloy valued for its tunable magnetic and electronic properties. These alloys can exhibit behaviors not seen in their individual elements, making them prime candidates for spintronic applications.

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