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Category: materials

Dynamically Tunable Singular States Through Air-Slit Control in Asymmetric Resonant Metamaterials

This study presents a novel method for dynamically tuning singular states in one-dimensional (1D) photonic lattices (PLs) using air-slit-based structural modifications. Singular states, arising from symmetry-breaking-induced resonance radiation, generate diverse spectral features through interactions between resonance modes and background radiation. By strategically incorporating air slits to break symmetry in 1D PLs, we demonstrated effective control of resonance positions, enabling dual functionalities including narrowband band pass and notch filtering. These singular states originate from asymmetric guided-mode resonances (aGMRs), which can be interpreted by analytical modeling of the equivalent slab waveguide. Moreover, the introduction of multiple air slits significantly enhances spectral tunability by inducing multiple folding behaviors in the resonance bands.

Void-Filled Material Stops Intense Electron Beam

An intense electron beam is stopped more efficiently by a highly porous material than by a less porous material, suggesting new strategies for controlling beams.

New experiments show that porous materials consisting mostly of empty space can absorb the energy carried by an ultraintense electron beam more effectively than porous media with higher mass densities. The finding contradicts the prevailing notion that denser and thicker obstacles always provide more stopping power and suggests that the microstructure of a material fundamentally changes its electron-stopping ability. Simulations by the experimental team revealed the physical mechanisms behind this “anomalous-stopping” effect, which the researchers believe provides a new way to control the propagation of electron beams in extreme environments [1].

The study focuses on relativistic electron beams (REBs), which travel at close to the speed of light. REBs that carry currents in the mega-ampere regime can deliver petawatts (1015 watts) of power to a small target in a pulse lasting for a few picoseconds. This high intensity makes them ideal for creating and probing extreme states of matter that exist in stars, planetary cores, or nuclear events. The short bursts of intense energy provided by REBs are also used in inertial-confinement fusion—a scheme in which high-power lasers heat a fuel pellet and trigger nuclear fusion.

LED light unlocks 3D optical fingerprints inside materials without lasers

Researchers have developed, for the first time in the world, incoherent dielectric tensor tomography (iDTT), a technology that can read complex three-dimensional optical fingerprints inside materials using only everyday LED illumination.

The study is published in Nature Photonics, and the research team was led by Professor YongKeun Park of the Department of Physics, in collaboration with Professor Seung-Mo Hong’s team at Asan Medical Center and Professor Seokwoo Jeon’s team at Korea University.

Some materials possess an inherent property called optical anisotropy, in which the refractive index changes depending on the direction in which light passes through. This is a decisive optical fingerprint that reveals the internal structure and molecular arrangement of the material.

Why twisted bilayer graphene stops superconducting near high-dielectric substrates

Superconductors are materials that can conduct electricity with a resistance of zero. In so-called conventional superconductors, this occurs at low temperatures when electrons become bound into pairs, known as Cooper pairs.

In some other materials, however, superconductivity (SC) emerges via other electron pairing mechanisms that are still poorly understood. These materials, called unconventional superconductors, include twisted bilayer graphene (tBLG), a two-dimensional material created by stacking two single sheets of graphene on top of each other, one of which is rotated in relation to the other by a precise small angle.

One factor that plays a role in unconventional SC is the so-called dielectric constant. This is the measure of how well a material reduces the electric forces between charged particles.

Magnetic ‘super lenses’ open new window on high-temperature superconductors

An international research team, including scientists from the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), has achieved a methodological breakthrough in the study of superhydrides, a promising class of superconductors. For the first time, the team succeeded in analyzing lanthanum superhydrides under extreme pressure using nuclear magnetic resonance spectroscopy.

The research is published in the journal Advanced Science.

Superconductors are characterized by the fact that their electrical resistance vanishes below a material-specific critical temperature, allowing them to conduct electricity without loss. For most known materials, this transition temperature is below about 140 Kelvin (minus 133 degrees Celsius), which requires complex cooling technology for practical applications. Consequently, researchers are actively searching for materials that exhibit superconductivity at significantly higher temperatures.

Sound waves create mist that can act like ‘plant sunscreen’

RMIT University researchers have developed a new way to coat fragile surfaces, including living plant leaves, using high‑frequency sound waves to create a fine mist that can act like a plant sunscreen.

The approach tackles a long‑standing challenge in materials science: many promising coatings require high temperatures or harsh processing, making them unsuitable for delicate surfaces such as living tissue, soft plastics or emerging electronic materials.

The research paper, “Ambient one‑step synthesis and direct coating of highly crystalline covalent organic frameworks on arbitrary surfaces,” is published in Science Advances.

Quantum geometry applied to light-based systems expands toolkit for topological photonics

Quantum geometry describes quantum states in systems with changing system parameters, such as an electron spinning in a magnetic field whose direction is slowly changing. The state of the electron evolves, and this change is quantified by what is known as the quantum geometric distance.

With the help of this abstract geometric description, it is possible, for example, to explain superconductivity—defined as the resistance-free conduction of current—in exotic quantum materials. Another example can be found in quantum metrology: by applying quantum geometry, fundamental limits on measurement accuracy can be determined.

Scientists program materials just by spinning them

There is something universally appealing about the slap bracelet, and the way a simple tap causes it to switch between a straight shape and a curled one. What you probably didn’t know is that a slap bracelet’s satisfying snap is the same principle behind bistable structures. These can toggle between two stable positions (one representing 0 and the other 1) to store data directly within their physical forms as mechanical bits (m-bits).

Because of their exciting potential for efficient control of robotic and other mechanical systems, researchers have been engineering special materials with programmable structures (programmable metamaterials) for years. But until now, actual programming of such systems has been a major challenge: mechanical bits must typically be controlled individually, which is extremely cumbersome and time-consuming.

Now, researchers in the Flexible Structures Laboratory (fleXLab) in EPFL’s School of Engineering, the Dutch research institute AMOLF, and Leiden University have found a way to program metamaterials globally with a surprisingly simple solution: rotation. By tuning a spinning platform’s speed, direction, and acceleration, the researchers can harness forces arising in a rotating system—such as centrifugal and Euler forces—to make elastic beams snap back and forth, creating a simple new way to “write” multiple mechanical bits at once.

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