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Category: materials – Page 2

New optical method reveals micellar structure changes under extensional stress

Complex fluids, such as polymer melts and concentrated suspensions, are foundational materials for industrial products, including high-strength plastics and optical components. The final performance of these materials depends on their composition and internal microscopic structure. During manufacturing processes, however, fluids are subjected to mechanical forces that introduce internal stress, leading to microscopic structural damage, which in turn affects the material’s functionality.

Despite the pressing need to observe and control this structure–stress relationship, few measurement techniques are available for fluids subjected to uniaxially extensional flow. Conventional optical techniques, owing to their low resolution and scope, fail to accurately track changes in the region of maximum stress, making it difficult to link mechanical stresses with observable optical changes.

Addressing this challenge, a research team from Nagoya Institute of Technology (NITech) in Japan, led by Assistant Professor Masakazu Muto recently developed a novel rheo-optical technique that can accurately characterize structural deformations in a complex fluid under extensional flow. Collaborators included Mr. Naoki Kako, Mr. Tatsuya Yoshino, and Professor Shinji Tamano.

New method uses spin motion to control heat flow in magnetic materials

NIMS, in joint research with the University of Tokyo, AIST, the University of Osaka, and Tohoku University, have proposed a novel method for actively controlling heat flow in solids by utilizing the transport of magnons—quasiparticles corresponding to the collective motion of spins in a magnetic material—and demonstrated that magnons contribute to heat conduction in a ferromagnetic metal and its junction more significantly than previously believed.

The creation of new principles “magnon engineering” for modulating thermal transport using magnetic materials is expected to lead to the development of thermal management technologies. This research result is published in Advanced Functional Materials.

Thermal conductivity is a fundamental parameter characterizing heat conduction in a solid. The primary heat carriers are known to be electrons and phonons, quasiparticles corresponding to lattice vibrations. In current thermal engineering, efforts are underway to modulate thermal conductivity and interfacial thermal resistance by elucidating and controlling the transport properties of heat carriers. In particular, heat conduction modulation focusing on the transport and scattering of phonons has been actively studied over the past decades as “phonon engineering.”

Room temperature electron behavior defies expectations, hinting at ultra-efficient electronics

Scientists have discovered a way to efficiently transfer electrical current through specific materials at room temperature, a finding that could revolutionize superconductivity and reshape energy preservation and generation.

The paper is published in the journal Physical Review Letters.

The much-sought-after breakthrough hinges on applying high pressure to certain materials, forcing their electrons closer together and unlocking extraordinary electronic behaviors.

Sugar-derived crystals show stiffness approaching that of aluminum

Mucic acid crystals grown from a water-based solution achieved a record-breaking stiffness for an organic crystal.

Stiffness is often described as the measure of resistance to deformation when a material is subjected to an external force. When we think of a stiff material, metals or ceramics usually come to mind, rather than crystals or organic molecules such as sugar or citric acid.

Hydrogen bonds have the ability to make even famously brittle and hard organic crystals ultrastiff.

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.

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