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Category: materials – Page 67

Water is usually something you’d want to keep away from electronic circuits, but engineers in Germany have now developed a new concept for water-based switches that are much faster than current semiconductor materials.

Transistors are a fundamental component of electronic systems, and in a basic sense they process data by switching between conductive and non-conductive states – zeroes and ones – as the semiconductor materials in them encounter electrical currents. The speed of this switching (along with the number of transistors in a chip) is a primary factor in how fast a computer system can be.

Now, researchers at Ruhr University Bochum have developed a new type of circuit that can switch much faster than existing semiconductor materials. The key ingredient is, surprisingly, water, with iodide ions dissolved into it to make it salty. A custom-made nozzle fans this water out into a flattened jet only a few microns thick.

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Graphene has been called “the wonder material of the 21st century.” Since its discovery in 2004, the material—a single layer of carbon atoms—has been touted for its host of unique properties, which include ultra-high electrical conductivity and remarkable tensile strength. It has the potential to transform electronics, energy storage, sensors, biomedical devices, and more. But graphene has had a dirty little secret: it’s dirty.

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In the last year, two independent groups have observed electrons behaving like quasiparticles with fractional amounts of charge, like –²⁄₃ and –³⁄₅, without the influence of a magnetic field.

In the 127 years since the electron was discovered, it has undergone more scrutiny than perhaps any other particle. As a result, its properties are not just well known, but rote, textbook material: Electrons have a smidgen of mass and negative electric charge. In a conductor, they swim relatively unimpeded as a current; in an insulator, they barely move.

Over time, caveats have cropped up. Under an intense magnetic field, for example, electrons can lose their individual identities and form “quasiparticles”: collective entities, like the shape formed by a school of fish. But even these collective states have been well cataloged.

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Group theory and first-principles calculations combine to predict which antiferromagnets have potentially useful net surface magnetization.

Antiferromagnetism was discovered in the 1930s by Louis Néel but had long been considered of scientific, not practical, interest. Antiferromagnets (AFM) are internally magnetic, but the magnetic moments of their atoms and molecules are antiparallel to each other, canceling out and resulting in no net magnetization. This cancellation renders bulk antiferromagnets effectively invisible to external magnetic fields, so that their magnetic properties are difficult to harness in applications. Recently, however, a new paradigm has appeared—antiferromagnetism-based spintronics—which seeks to apply antiferromagnets’ unique properties (such as fast spin dynamics, the absence of strong stray fields, and the stability of these materials) to the processing and storage of information [1].

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Lithium-ion batteries have been at the forefront of energy storage technologies. However, the availability of lithium is limited. Consequently, the growing demand for energy-storage systems has led to the search for low-cost and more accessible materials for rechargeable batteries. Sodium-ion batteries (SIBs) are a promising candidate due to the virtually unlimited sodium (Na) resources in seawater and salt deposits.

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One way to manage the unsustainable energy requirements of the computing sector is to fundamentally change the way we compute. Superconductors could let us do just that.

Superconductors offer the possibility of drastically lowering energy consumption because they do not dissipate energy when passing current. True, superconductors work only at cryogenic temperatures, requiring some cooling overhead. But in exchange, they offer virtually zero-resistance interconnects, digital logic built on ultrashort pulses that require minimal energy, and the capacity for incredible computing density due to easy 3D chip stacking.

Are the advantages enough to overcome the cost of cryogenic cooling? Our work suggests they most certainly are. As the scale of computing resources gets larger, the marginal cost of the cooling overhead gets smaller. Our research shows that starting at around 10 16 floating-point operations per second (tens of petaflops) the superconducting computer handily becomes more power efficient than its classical cousin. This is exactly the scale of typical high-performance computers today, so the time for a superconducting supercomputer is now.

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Our is capable of demonstrating high spectral resolution and accurate reconstruction of full-Stokes polarization states in both theoretical and experimental settings. Precision detection of high-dimensional information by our photodetector, such as a two-color laser field with different polarization states or broadband reflection from a gold interface exhibiting varying states, is achieved beyond the capabilities of commercial polarimeter and spectrometer.

Additionally, this approach can be extended to imaging applications by sandwiching the film with a commercial microlens array and sensor array to realize ultra-compact high-dimensional imager, said Assistant Professor Chunqi Jin from the Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP) of the Chinese Academy of Sciences.

Looking ahead, Prof. Wei Li envisions that ultra-broadband detection can be achieved by integrating broadband commercial photodetectors; the detection resolution can be further improved by using , metasurfaces, and two-dimensional materials instead of existing thin film schemes; and the detection capability can be stepped up in higher dimensions by integrating functionalities such as , and distance measurement.

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Making use of some of the most powerful telescopes on the planet, astronomers have found an ancient remnant of the Big Bang. This small piece of pure material from the early universe may provide light on the processes and motivations behind the formation of various star and galaxy types.

Using telescopes at the W. M. Keck Obervatory in Hawaii, a team of astronomers led by Fred Robert and Michael Murphy of the Swinburne University of Technology in Australia discovered a cloud of gas leftover from the Big Bang that was hiding far out in the universe. Behind the cloud, the telescope also discovered a quasar, which is an extremely bright active galactic nucleus that emits a lot of energy.

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What if a common element rather than scarce, expensive ones was a key component in electric car batteries?

A collaboration co-led by an Oregon State University chemistry researcher is hoping to spark a green battery revolution by showing that iron instead of cobalt and nickel can be used as a cathode material in lithium-ion batteries.

The findings, published today in Science Advances, are important for multiple reasons, Oregon State’s Xiulei “David” Ji notes.

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The public’s appetite for inexpensive and powerful electronic devices continues to grow. While silicon-based semiconductors have been key to satiating this demand, a superior alternative could be wide-bandgap semiconductors. These materials, which operate at higher temperatures and handle increased power loads, are unfortunately very expensive.

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