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Category: materials – Page 150

LK-99: Diamagnetc Semiconductor, Not Superconductor?

Every so often, along comes a story which, like [Fox Mulder] with his unexplained phenomena, we want to believe. EM drives and cold fusion for example would be the coolest of the cool if they worked, but sadly they crumbled when subjected to scientific inquiry outside the labs of their originators. The jury’s still out on the latest example, a claimed room-temperature superconductor, but it’s starting to seem that it might instead be a diamagnetic semiconductor.

We covered some of the story surrounding the announcement of LK-99 and subsequent reports of it levitating under magnetic fields, but today’s installment comes courtesy of a team from Beihang University in Beijing. They’ve published a paper in which they characterize their sample of LK-99, and sadly according to them it’s no superconductor.

Instead it’s a diamagnetic semiconductor, something that in itself probably bears some explanation. We’re guessing most readers will be familiar with semiconductors, but diamagnetic substances possess the property of having an external magnetic field induce an internal magnetic field in the opposite direction. This means that they will levitate in a magnetic field, but not due to the Meissner effect, the property of superconductors which causes magnetic field to flow round their outside. The Beijing team have shown by measuring the resistance of the sample that it’s not a superconductor.

Sensing and controlling microscopic spin density in materials

Electronic devices typically use the charge of electrons, but spin — their other degree of freedom — is starting to be exploited. Spin defects make crystalline materials highly useful for quantum-based devices such as ultrasensitive quantum sensors, quantum memory devices, or systems for simulating the physics of quantum effects. Varying the spin density in semiconductors can lead to new properties in a material — something researchers have long wanted to explore — but this density is usually fleeting and elusive, thus hard to measure and control locally.

Now, a team of researchers at MIT and elsewhere has found a way to tune the spin density in diamond, changing it by a factor of two, by… More.

MIT researchers found a way to tune the spin density in diamond by applying an external laser or microwave beam. The finding could open new possibilities for advanced quantum devices.

Unleashing Photonic Power: Groundbreaking Advancements in Optical Computing

In a breakthrough for optical computing, researchers developed a nanosecond-scale volatile modulation scheme integrating a phase-change material.

Technological advancements such as autonomous driving and computer vision have spurred a significant increase in demand for computational power. Optical computing, characterized by its high throughput, energy efficiency, and low latency, has attracted significant interest from both academia and industry. However, current optical computing chips are hampered by their power consumption and size, which limit the scalability of optical computing networks.

Nonvolatile integrated photonics has emerged to address these issues, offering optical computing devices the ability to perform in-memory computing while operating with zero static power consumption. Phase-change materials (PCMs), with their high refractive index contrast between different states and reversible transitions, have become promising candidates for enabling photonic memory and nonvolatile neuromorphic photonic chips. This makes PCMs ideally suited for large-scale nonvolatile optical computing chips.

Unraveling the Mysteries of Topology: Scientists Debunk Existing Assumptions

Topology has become a critical factor in the field of modern condensed matter physics and beyond. It explains the way solid materials may possess two distinct and seemingly conflicting characteristics. An example of this is topological insulators, materials whose bulk acts as an insulator, and can still conduct electricity at their surfaces and edges.

Over the past several decades, the idea of topology has revolutionized the understanding of electronic structure and the overall properties of materials. Additionally, it has opened doors to technological advancements by facilitating the integration of topological materials into electronic applications.

At the same time, topology is quite tricky to measure, often requiring combinations of multiple experimental techniques such as photoemission and transport measurements. A method known as high harmonic spectroscopy has recently emerged as a key technique to observe the topology of a material. In this approach a material is irradiated by intense laser light.

Waves of charge signal rare physics at work inside a superconductor

“A place for everything and everything in its place”—making sense of order, or disorder, helps us understand nature. Animals tend to fit nicely into categories: Mammals, birds, reptiles, whatever an axolotl is, and more. Sorting also applies to materials: Insulator, semiconductor, conductor, and even superconductor. Where exactly a material lands in the hierarchy depends on a seemingly invisible interplay of electrons, atoms, and their surroundings.

Unlike animals, the boundaries are less sharp, and tweaking a material’s environment can force it to bounce between categories. For example, dialing down the temperature will turn some into superconductors. Snapping on a might reverse this effect. Within a single category, different types of order, or phases, can emerge from the sea of particles.

Unfortunately, we can’t see this nanoscopic universe with our eyes, but scientists can use advanced imaging tools to visualize what’s going on. Every once in a while, they uncover unexpected and surprising behaviors.

Webb Space Telescope captures stunning shots of Ring Nebula

The main ring is surrounded by a faint halo and with many delicate structures. The interior of the ring is filled with hot gas. The star which ejected all this material is visible at the very center. It is extremely hot, with a temperature in excess (NASA, ESA, CSA, JWST Ring Nebula Team photo; image processing by Roger Wesson)

The images were released Thursday by an international team of astronomers, including three from the Canadian Western University’s Institute for Earth and Space Exploration.

Amazon Just Signaled It’s Serious About Dominating This $600 Billion Industry

For a company the size of Amazon, it takes a lot to move the needle. It’s hard to enter new businesses that have enough upside to make a material difference. Advertising is one of them. With its recent change to break out results for its advertising business, Amazon is signaling it’s all in on staking its claim to as much of the market as it can.

That market is growing, but Amazon’s business is growing much faster. That means it’s taking share away from its competitors. Amazon is already the third-largest advertising platform. I wouldn’t bet against it someday soon becoming the biggest.

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Single drop of ethanol to revolutionize nanosensor manufacture

Macquarie University engineers have developed a new technique to make the manufacture of nanosensors far less carbon-intensive, much cheaper, more efficient, and more versatile, substantially improving a key process in this trillion-dollar global industry.

The team has found a way to treat each sensor using a single drop of instead of the conventional process that involves heating materials to high temperatures.

Their research, published in Advanced Functional Materials, is titled, ‘Capillary-driven self-assembled microclusters for highly performing UV detectors.’

Research team develops the fastest neuromorphic, electric double layer transistor

A research team consisting of the National Institute for Materials Science (NIMS) and the Tokyo University of Science has developed the fastest electric double layer transistor using a highly ion-conductive ceramic thin film and a diamond thin film.

This transistor may be used to develop energy-efficient, high-speed edge AI devices with a wide range of applications, including future event prediction and /determination in images (including ), voices and odors. This research was published in the June 16, 2023, issue of Materials Today Advances.

An electric double layer transistor works as a switch using electrical resistance changes caused by the charge and discharge of an electric double layer formed at the interface between the electrolyte and semiconductor. Because this transistor is able to mimic the electrical response of human cerebral neurons (i.e., acting as a neuromorphic transistor), its use in AI devices is potentially promising.

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