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Category: materials

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.

This Crystal Doesn’t Melt Like Ice: Physicists Capture a Strange New Phase

New research offers clearer insight into how phase transitions unfold at the atomic scale in real materials. When ice turns into water, the change happens almost instantly. Once the melting temperature is reached, the rigid structure of the solid collapses and becomes a flowing liquid. This abrup

Scientists discover that gold is a ‘reactive metal’ by accidentally creating a new material in the lab

In a high-pressure lab experiment, scientists accidentally created a new compound called gold hydride. This particular hydride formed when thin gold foil met dense hydrogen at pressures hundreds of thousands of times Earth’s atmosphere and blazing temperatures.

The discovery challenges gold’s reputation as a nearly inert metal and shows how extreme conditions can push familiar materials into unfamiliar forms.

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.

Journey to the center of a quantized vortex: How microscopic mutual friction governs superfluid dissipation

Step inside the strange world of a superfluid, a liquid that can flow endlessly without friction, defying the common-sense rules we experience every day, where water pours, syrup sticks and coffee swirls and slows under the effect of viscosity. In these extraordinary fluids, motion often organizes itself into quantized vortices: tiny, long-lived whirlpools that act as the fundamental building blocks of superfluid flow.

An international study conducted at the European Laboratory for Non-Linear Spectroscopy (LENS), involving researchers from CNR-INO, the Universities of Florence, Bologna, Trieste, Augsburg, and the Warsaw University of Technology, has embarked on this journey by investigating the dynamics of vortices within strongly interacting superfluids, uncovering the fundamental mechanisms that govern their behavior.

Using ultracold atomic gases, the scientists open a unique window into this exotic realm, recreating conditions similar to those found in superfluid helium-3, the interiors of neutron stars, and superconductors.

Anything-goes “anyons” may be at the root of surprising quantum experiments

In the past year, two separate experiments in two different materials captured the same confounding scenario: the coexistence of superconductivity and magnetism. Scientists had assumed that these two quantum states are mutually exclusive; the presence of one should inherently destroy the other.

Now, theoretical physicists at MIT have an explanation for how this Jekyll-and-Hyde duality could emerge. In a paper appearing today in the Proceedings of the National Academy of Sciences, the team proposes that under certain conditions, a magnetic material’s electrons could splinter into fractions of themselves to form quasiparticles known as “anyons.” In certain fractions, the quasiparticles should flow together without friction, similar to how regular electrons can pair up to flow in conventional superconductors.

If the team’s scenario is correct, it would introduce an entirely new form of superconductivity — one that persists in the presence of magnetism and involves a supercurrent of exotic anyons rather than everyday electrons.

Engineered dendritic cells boost cancer immunotherapy

EPFL researchers have successfully engineered cells of the immune system to more effectively recognize cancer cells. The work, covered in two papers, turns the previously lab-based method into a full-blown immunotherapy strategy.

Cancer immunotherapy is a strategy that turns the patient’s own immune cells into a “search-and-destroy” force that attacks the tumor’s cells. The “search” immune cells are the dendritic cells, which collect and present identifying parts of the cancer cells (antigens) to the “destroy” part (T cells), the immune system’s killer cells.

The problem is that many tumors “learn” how to evade detection by the patient’s dendritic cells. Clinicians address this by collecting dendritic cells from the patient’s blood, loading them in the laboratory with tumor material—antigens that train dendritic cells to better identify the tumor—and then injecting them back into the patient.

Controlling exciton flow in moiré superlattices: New method leverages correlated electrons

Excitons are pairs of bound negatively charged electrons and positively charged holes that form in semiconductors, enabling the transport of energy in electronic devices. These pairs of charge carriers also emerge in transition metal dichalcogenides, thin semiconducting materials comprised of a transition metal and two chalcogen atoms.

Researchers at Carnegie Mellon University, UC Riverside, and other institutes have introduced a new strategy to control the flow of energy in structures comprised of two transition metal dichalcogenide layers stacked with a small rotational mismatch, also known as moiré superlattices.

Their proposed approach, introduced in a paper published in Nature Communications, entails the active tuning of electronic states in moiré superlattices in ways that alter the transport of excitons.

Invisible heat insulators

Researchers in Science have developed a clear, high-insulating material they say could be used to produce ultra-efficient windows and thus reduce the energy use of buildings dramatically worldwide.

Learn more in a new Science Perspective.

A nanotube network with precisely engineered pores could replace insulating components in windows.

Longnan Li and Wei Li Authors Info & Affiliations

Science

Vol 390, Issue 6778

Continue reading “Invisible heat insulators” | >

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