Photonic crystals are materials with repeating internal structures that interact with light in unique ways. We can find natural examples in opals and the vibrant colored shells of some insects. Even though these crystals are made of transparent materials, they exhibit a “photonic bandgap” that blocks light at certain wavelengths and directions.
Understanding how light travels through various materials is essential for many fields, from medical imaging to manufacturing. However, due to their structure, materials often show directional differences in how they scatter light, known as anisotropy. This complexity has traditionally made it difficult to accurately measure and model their optical properties. Recently, researchers have developed a new technique that could transform how we study these materials.
TU Wien (Vienna) has succeeded in generating laser-synchronized ion pulses with a duration of well under 500 picoseconds, which can be used to observe chemical processes on material surfaces. The work has been published in Physical Review Research.
Getting tips from the design of the human body.
Scientists create bone-inspired cement, over five times stronger than concrete.
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A team of researchers from the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) in Hamburg, Germany, and Brookhaven National Laboratory in the United States has demonstrated a new way to study disorder in superconductors using terahertz pulses of light.
NiO-functionalized graphene sensor detects ammonia in real time, offering a powerful tool for monitoring beef freshness and ensuring food safety.
The widespread use of artificial intelligence (AI) tools designed to process large amounts of data has increased the need for better performing memory devices. The data storage solutions that could help to meet the computational demands of AI include so-called high-bandwidth memories, technologies that can increase the memory bandwidth of computer processors, speeding up the transfer of data and reducing power consumption.
Currently, flash memories are the most prominent memory solutions capable of storing information when a device is turned off (i.e., non-volatile memories). Despite their widespread use, the speed of most existing flash memories is limited and does not best support the operation of AI.
In recent years, some engineers have thus been trying to develop ultrafast flash memories that could transfer data faster and more efficiently. Two-dimensional (2D) materials have shown promise for fabricating these better performing memory devices.
In the realm of lighting and temperature measurement, advancements in material science are paving the way for significant improvements in technology and safety. Traditional methods, which combine yellow phosphors with blue chips in LEDs, have limitations such as inadequate red light components that affect color rendering and potential hazards from blue light exposure.
A team of researchers from Texas A&M University, Sandia National Lab — Livermore, and Stanford University are taking lessons from the brain to design materials for more efficient computing. The new class of materials discovered is the first of their kind – mimicking the behavior of an axon by spontaneously propagating an electrical signal as it travels along a transmission line. These findings could be critical to the future of computing and artificial intelligence.
This study was published in Nature (“Axon-like active signal transmission”).
Any electrical signal propagating in a metallic conductor loses amplitude due to the metal’s natural resistance. Modern computer processing (CPU) and graphic processing units can contain around 30 miles of fine copper wires moving electrical signals around within the chip. These losses quickly add up, requiring amplifiers to maintain the pulse integrity. These design constraints impact the performance of current interconnect-dense chips.
Orbital currents are the lesser-known cousins of spin currents. Both involve an alignment of angular momentum. But spin currents are carried by spin-polarized electrons, while orbital currents are carried by electrons in orbitals having the same angular momentum. Like their spin counterparts, orbital currents could be useful for transmitting information in so-called orbitronic devices, but researchers had expected that these currents would not travel well across material interfaces. Now Igor Lyalin and Roland Kawakami from Ohio State University have measured the flow of orbital currents across selected materials placed in multilayer structures. They find, surprisingly, that the transport of orbital currents is as good or better than the transport of spin currents for most of the sampled materials.
Orbital currents can be generated via the so-called orbital Hall effect—a surface magnetization effect that was predicted 20 years ago but directly detected only in 2023 (see Synopsis: Detection of the Orbital Hall Effect). Interest in orbital currents is growing, as they could be more effective than spin currents at switching the orientation of magnetic layers in data-storage devices.
To study orbital current transport, Lyalin and Kawakami fabricated structures consisting of chromium and nickel layers, separated by a thin spacer. For the spacer material, they tested nonmagnetic metals, ferromagnetic metals, and antiferromagnetic insulators. The researchers generated an orbital current by applying a voltage to the chromium layer, and they measured how much of this current flowed through the structures by observing a magnetization change in the nickel. They found that 12 of the 15 spacer materials transported orbital currents more efficiently than spin currents—a result that could be good news for developing future orbitronic devices, Kawakami says.
