Lifeboat Foundation: Safeguarding Humanity
Toggle light / dark theme

Blog

Category: materials

Phonon lasers unlock ultrabroadband acoustic frequency combs

Acoustic frequency combs organize sound or mechanical vibrations into a series of evenly spaced frequencies, much like the teeth on a comb. They are the acoustic counterparts of optical frequency combs, which consist of equally spaced spectral lines and act as extraordinarily precise rulers for measuring light.

While optical frequency combs have revolutionized fields such as precision metrology, spectroscopy, and astronomy, acoustic frequency combs utilize sound waves, which interact with materials in fundamentally different ways and are well-suited for various sensing and imaging applications.

However, existing acoustic frequency combs operate only at very high, inaudible frequencies above 100 kHz and typically produce no more than a few hundred comb teeth, limiting their applicability.

Chemists synthesize first stable copper metallocene complex, closing a 70-year gap

Almost half a century ago, a remarkable molecule called metallocene took center stage in chemistry, earning Geoffrey Wilkinson and Ernst Otto Fischer the Nobel Prize. These organic compounds, made of a transition metal “sandwiched” between two flat, ring-shaped organic layers, have since become an integral part of new-age polymers, materials, and pharmaceuticals.

In their recent work published in the Journal of the American Chemical Society, a team from University of California brought metallocene back into the limelight with the synthesis of cuprocenes—the first stable version of neutral copper metallocene with the chemical formula Cpttt 2 Cu where Cpttt stands for C5H2tBu3 or bis(tri-tert-butylcyclopentadienyl) ligand. This new complex of copper has blue-green crystals and is stable at room temperature, away from light.

They also produced two new forms of cuprocene: a colorless, negatively charged version via reduction, and a purple, positively charged version via oxidation.

Obstacle or accelerator? How imperfections affect material strength

Imagine a material cracking—now imagine what happens if there are small inclusions in the material. Do they create an obstacle course for the crack to navigate, slowing it down? Or do they act as weak points, helping the crack spread faster?

Historically, most engineers believed the former, using heterogeneities, or differences, in materials to make materials stronger and more resilient. However, research from Georgia Tech is showing that, in some cases, heterogeneities make materials weaker and can even accelerate cracks.

Led by School of Physics Assistant Professor Itamar Kolvin, the study, “Dual Role for Heterogeneity in Dynamic Fracture,” was published in Physical Review Letters this fall.

What ‘housane’ rings are and why a light-powered route may matter for drugs

When developing new drugs, one thing is particularly important: finding and producing the right molecules that can be used as active ingredients. The key elements of some drugs, such as penicillin, are small, tri- or quadripartite ring molecules. A team led by Prof Frank Glorius from the Institute of Organic Chemistry of the University of Münster (Germany) has now developed a method for efficiently converting readily available basic materials into such small, high-grade ring molecules. The product has a structure reminiscent of a line drawing of a house, hence its name “housane.” The reaction is triggered by a photocatalyst that transfers light energy to the molecules to enable the conversion.

Silicon nanowire based angle robust ultrasensitive hyperbolic metamaterial biosensor

We design an angle-robust hyperbolic metamaterial-based biosensor structure using n-doped silicon nanowires. We examine the hyperbolic properties of the structure using effective medium theory (EMT) and analyze the resonance shift of our proposed biosensor structure, by employing the finite-difference time d.

Strong correlations and superconductivity observed in a supermoiré lattice

Two or more graphene layers that are stacked with a small twist angle in relation to each other form a so-called moiré lattice. This characteristic pattern influences the movement of electrons inside materials, which can give rise to strongly correlated states, such as superconductivity.

Researchers at Ecole Polytechnique Fédérale de Lausanne, Freie Universität Berlin and other institutes recently uncovered a strong superconductivity in a supermoiré lattice, a twisted trilayer graphene structure with broken symmetry in which several moiré patterns overlap. Their paper, published in Nature Physics, could open new possibilities for the design of quantum materials for various applications.

“Fabricating a twisted trilayer graphene device with two distinct twist angles was not our original intention,” Mitali Banerjee, senior author of the paper, told Phys.org. “Instead, we aimed to make a device in which the two twist angles are identical in magnitude (magic-angle twisted trilayer). During our measurements, however, my student Zekang Zhou found that the phase diagram of this device differs fundamentally from that of magic-angle twisted trilayer graphene.”

Dimerization-dependent gel-like condensation with dsDNA underpins the activation of human cGAS

CGAS forms condensates on cytosolic double-stranded (ds)DNA and initiates inflammatory responses. Lueck et al. find that, although cGAS forms condensates on various nucleic acids, it enters a hydrogel-like state only with dsDNA via dimerization. The gel-like cGAS condensate not only protects bound dsDNA from exonucleases but also facilitates catalysis.

Twisted 2D magnet creates skyrmions for ultra dense data storage

As data keeps exploding worldwide, scientists are racing to pack more information into smaller and smaller spaces — and a team at the University of Stuttgart may have just unlocked a powerful new trick. By slightly twisting ultra-thin layers of a magnetic material called chromium iodide, researchers created an entirely new magnetic state that hosts tiny, stable structures known as skyrmions — some of the smallest and toughest information carriers ever observed.

Electrically controllable 3D magnetic hopfions realized in chiral magnets

A research team from the High Magnetic Field Laboratory of the Hefei Institutes of Physical Science of the Chinese Academy of Sciences, together with collaborators from Anhui University, ShanghaiTech University, and the University of New Hampshire, has demonstrated the first electrically controllable generation of hopfions—three-dimensional topological solitons—in a solid-state magnetic system. The results are published online in Nature Materials.

Proposed in 1975, hopfions are three-dimensional topological structures characterized by a Hopf charge and capable of forming rings, links, and knots. Although they are predicted to exist in a wide range of physical systems—from magnetic materials and plasmas to the early universe—their complexity has kept hopfions largely confined to theory, with only limited experimental realization and control.

In this study, the researchers used a chiral magnet as a laboratory test bed. By applying spin-transfer torque together with thermal excitation, they successfully generated magnetic hopfions in the chiral magnet FeGe.

/* */