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Category: materials – Page 2

Twisted ultrathin magnet retains magnetization after field changes, study finds

The properties of ultrathin magnets can be specifically altered by a slight twist between two atomic monolayers. This is the conclusion reached by an international research team led by TU Darmstadt in a study published in Nature Communications. The findings open new prospects for future memory devices.

For the first time, the researchers observed that an extremely thin magnetic material—a so-called two-dimensional van der Waals magnet—” stores” its magnetic state: It responds to a magnetic field and retains some of its magnetization even when the applied field changes. This “memory” is known as hysteresis and forms the basis of many data storage systems.

Astronomers may have caught an early galaxy in the process of dying

Astronomers have spotted many “red and dead” galaxies in the early universe. These are massive systems that stopped forming stars surprisingly early in cosmic history. Now, they may have found evidence of one in the act of becoming dead: a massive galaxy being stripped of its starforming gas just 1.4 billion years after the Big Bang. The clues behind why it lost its star-forming material are detailed in a paper posted to the arXiv preprint server on June 16.

Comet-like galaxy SPT2349–56 is an emerging galaxy cluster, or “protocluster,” containing about 30 star-forming galaxies within a region 100 kiloparsecs wide. Among its members, C26 is particularly interesting because of its unusual shape. It has a head and a tail like a comet. It also has a dense, bright region called the “knot,” embedded within the tail. It was first detected in ALMA images.

In this new study, using observations from the Hubble Space Telescope and the James Webb Space Telescope, the team led by Dazhi Zhou of the University of British Columbia studied this galaxy’s head, tail and knot to estimate its mass and star-forming properties.

World-first neutron lens brings sharp focus to structures inside materials and objects

Researchers at Paul Scherrer Institute (PSI) have developed the world’s first achromatic lens for neutron imaging. The lens overcomes a longstanding obstacle in the field: focusing neutrons of different wavelengths well enough to form a sharp, magnified image. With the lens, researchers can now image thick samples and follow processes inside bulky equipment such as furnaces, cryostats or pressure cells.

Neutrons can provide unique insights into the structure of materials—but they are hard to manipulate. Neutrons, like X-rays, are produced as a beam at research facilities such as the Swiss Spallation Neutron Source SINQ and are used to image inside materials and objects. Unlike X-rays, however, neutrons can penetrate deeply into many metals while remaining highly sensitive to light elements such as hydrogen and lithium. In this way, they can be used to observe oil, polymer or lithium distribution inside dense metallic structures such as engines or batteries, reveal water uptake in plants or nondestructively examine priceless archaeological artifacts.

Yet the same weak interaction with matter that makes neutrons such a useful tool also makes them notoriously difficult to deflect or focus—a fact that has limited the development of advanced imaging techniques. Now, PSI scientists have reported in Nature Communications a new type of lens that overcomes this barrier.

Bio-metal: Exploring the metallic mystery of an ancient maw

When playing the classic game “20 Questions,” one may begin with the common opener: “Animal, vegetable, or mineral?”

For the ancient sea worm Perinereis cultrifera (which is still around today), the answer might not be so simple. Along with other predatory bristle worms, Perinereis cultrifera has jaws made from structural proteins and ions, which it uses for eating, crushing or biting. The unique makeup and properties of these jaws led some researchers to coin a new term to describe these types of materials: bio-metals, an emerging field of biophysical study.

The term “bio-metal” goes beyond identifiers like “metallike biomaterials” or “biomaterials with metallike properties,” which have been used in scientific literature to describe biomaterials with conductivity or strength values similar to metals. Instead, bio-metals can be categorized by three qualities: hardness, strain mechanics and ion-protein structure.

Hubble discovers first of star cluster’s missing black holes

The massive globular star cluster Omega Centauri has puzzled astronomers for decades. It should be filled with black holes left behind by exploding stars, yet evidence for them is scarce. Now, astronomers using archival data from NASA’s Hubble Space Telescope and supporting observations from NASA’s James Webb Space Telescope have finally located the first stellar-mass black hole in this cluster. Discovering the first of this missing black hole population will help refine current theories on black hole formation within environments such as Omega Centauri. The team’s findings were published in The Astrophysical Journal Letters.

Omega Centauri consists of 10 million gravitationally bound stars. Though the astronomical community previously found evidence using Hubble that an intermediate-mass black hole lurks at its center, models suggest this star cluster should also contain about 10,000 smaller, stellar-mass black holes. This notable population of black holes evaded detection in previous observational studies, which used the radial velocity method or looked for radio and X-ray emission from material falling onto black holes.

New imaging method reveals how electric fields reshape ferroelectric materials

New research is shedding light on longstanding debates over the behavior of ferroelectric materials when those materials are exposed to electric fields. The findings stem from the use of a novel technique that allows researchers to observe the real-time behavior of domain walls in ferroelectric materials as they are “poled” and “depoled.”

Ferroelectric materials are used in a wide range of technologies, from sensors to actuators, and their electrical properties are critical to their utility. It’s well established that you can bring the various domains in a ferroelectric material into alignment by applying an electric field—either direct current (DC) or alternating current (AC). This is called “poling.” However, there has been significant debate about what exactly is taking place during the poling process.

“We’re now able to observe what is happening in real time, which gives us deeper insights into the mechanisms at play—which will inform our ability to engineer materials in order to produce the electrical characteristics we’re looking for,” says Jun Liu, co-corresponding author of two papers on the work and an associate professor of mechanical and aerospace engineering at North Carolina State University.

MIT engineers whip up a more breathable hydrogel

For all their sticky, stretchy, and protective properties, hydrogels lack one key trait: breathability. If worn for too long, a bandage or patch can trap moisture and sweat, which can irritate tissues and reduce the effectiveness of any device that a hydrogel adheres.

Now MIT engineers have come up with a recipe for a hydrogel that is both hydrated and aerated, or permeable to air. The new material is just as soft, stretchy, and robust as conventional hydrogels, but a network of tiny tunnels running through the gel allows air to pass through.

The aerated hydrogel can be worn for longer periods of time compared to conventional hydrogels, without causing skin irritation. It can also reduce sweat buildup, even during exercise. In experiments, volunteers wore wireless heart monitors that were attached to their chest with the new breathable hydrogel. After working out regularly for 10 days, the volunteers showed no signs of skin irritation, and the heart monitors maintained clear readings.

Physicists finally build a quantum material predicted more than a decade ago

Researchers have achieved a major milestone by creating a long-sought two-dimensional quantum material and confirming its unusual conducting edge states. The ability to control these states through strain could make the material a promising platform for future room-temperature quantum electronics.

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