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Category: materials – Page 4

Amplified spontaneous emission is a physical phenomenon that entails the amplification of the light spontaneously emitted by excited particles, due to photons of the same frequency triggering further emissions. This phenomenon is central to the functioning of various optoelectronic technologies, including lasers and optical amplifiers (i.e., devices designed to boost the intensity of light).

The excitation of a material with high-energy photons can produce what is known as an electron-hole . This state is characterized by the dense presence of negatively charged particles (i.e., electrons) and positively charged vacancies (i.e., holes).

Researchers at Wuhan University recently observed amplified spontaneous emission originating from degenerate electron-hole plasma in a 2D semiconductor, namely suspended bilayer tungsten disulfide (WS2). Their paper, published in Physical Review Letters, could pave the way for the development of new optoelectronic technologies based on 2D semiconductors.

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Researchers have uncovered a surprising phenomenon in the material BiNiO3: when subjected to high pressure at low temperatures, its well-arranged electrical charges are disrupted, leading to a disordered “charge glass” state.

The study is published in the journal Nature Communications.

This discovery offers new insights into how materials respond to , potentially paving the way for new advanced materials with unique and useful properties.

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Korean researchers have succeeded in developing a key technology for all-solid-state secondary batteries, known as next-generation lithium-ion batteries due to their high safety. The work was published online as a cover study in Small at the end of last year.

Electronics and Telecommunications Research Institute (ETRI) developed a separation membrane based on a material that easily becomes fibrillized when subjected to mechanical shearing (force applied) through a mixing process with solid electrolyte powder without using a solvent. This solid electrolyte membrane is simple and fast to manufacture and is extremely thin and robust.

In general, in research on all-solid-state secondary batteries, the thickness is set to several hundred micrometers (µm) to 1 millimeter (mm) to increase the durability of the membrane when using a hard solid electrolyte in the manufacturing process. However, this has the disadvantage of being too thick compared to conventional polymer separation membranes, resulting in a very large loss of energy density.

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A Stanford study shows that electrical charges in sprays of water can cause chemical reactions that form organic molecules from inorganic materials. The findings provide evidence that microlightning may have helped create the building blocks necessary for early life on the planet.

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Japan is home to a wide variety of train stations, from tiny countryside sheds to sprawling urban complexes, stations with their own wineries and ones with giant ancient relics whose eyes glow. It’s gotten to the point where it’s really hard to be “the first” anything when it comes to train stations, but JR West has managed it with the first-ever 3D-printed station building.

This new structure is scheduled to replace the current one at Hatsushima Station on the JR Kisei Main Line in Arida City, Wakayama Prefecture. Like many relatively rural stations in Japan, the wooden structures are aging and in need of replacements.

The new building will be roughly the same size, covering 10 square meters (108 square feet) and made from a more durable reinforced concrete. The foundation and exterior of the building will be printed off-site by Osaka-based 3D-printer housing company Serendix.

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Altermagnets are arguably the hottest objects in magnetism right now (see Viewpoint: Altermagnetism Then and Now). Over the past year, researchers have delivered experimental evidence for this new type of magnet, but they have yet to harness the behavior for applications. Now three independent groups have proposed methods for electrically tuning the properties of altermagnets [1– 3]. If implemented, the findings could allow the use of altermagnets in next-generation spintronics devices.

Altermagnets can be thought of as a cross between antiferromagnets and ferromagnets. Like antiferromagnets the materials lack net magnetization—the magnetic spins of the atomic lattice are aligned in opposing directions. Like ferromagnets they have magnetically sensitive energy levels and display electronic band structures that are split into spin-up and spin-down bands. This splitting can be used to polarize an electronic current, as one spin state will flow through the material more easily. The combination of these properties could allow researchers to create spintronics devices that operate more rapidly and with greater efficiency than those currently in use, but for that, they first need a way to manipulate the spin properties of an altermagnet.

The proposed methods of the three teams (a group led by Tong Zhou of the Eastern Institute of Technology, Ningbo, China; Libor Šmejkal of the Max Planck Institute for the Physics of Complex Systems, Germany; and a group led by Qihang Liu of the Southern University of Science and Technology, China) all use electric fields for this switching. Controlling magnetism with electricity is particularly attractive because electric fields are much easier to manipulate and integrate into modern electronic devices than magnetic fields. Electrical tuning is potentially also faster (subnanosecond) and could use less energy, two crucial properties for the development of high-speed, low-power spintronic devices.

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Scientists have unlocked a way to read magnetic orientation at record-breaking speeds using terahertz.

Terahertz radiation refers to the electromagnetic waves that occupy the frequency range between microwaves and infrared light, typically from about 0.1 to 10 terahertz (THz). This region of the electromagnetic spectrum is notable for its potential applications across a wide variety of fields, including imaging, telecommunications, and spectroscopy. Terahertz waves can penetrate non-conducting materials such as clothing, paper, and wood, making them particularly useful for security screening and non-destructive testing. In spectroscopy, they can be used to study the molecular composition of substances, as many molecules exhibit unique absorption signatures in the terahertz range.

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“‘Incipient ferroelectricity’ means there’s no stable ferroelectric order at room temperature,” lead author Dipanjan Sen explains of the property that the team investigated. “Instead, there are small, scattered clusters of polar domains. It’s a more flexible structure compared to traditional ferroelectric materials.”

Typically, the “relaxor” behavior of incipient ferroelectric materials at room temperature is a drawback, making their operation less predictable and more fluid — but the team’s breakthrough was to approach it as an advantage instead, showing how it could be of use in devices like neuromorphic processors that increase machine learning and artificial intelligence performance by processing information like the neurons in the human brain.

“To test this,” co-author Mayukh Das says, “we performed a classification task using a grid of three-by-three pixel images fed into three artificial neurons. The devices were able to classify each image into different categories. This learning method could eventually be used for image identification and classification or pattern recognition. Importantly, it works at room temperature, reducing energy costs. These devices function similarly to the nervous system, acting like neurons and creating a low-cost, efficient computing system that uses a lot less energy.”

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