Researchers at Kumamoto University and Nagoya University have developed a new class of two-dimensional (2D) metal-organic frameworks (MOFs) using triptycene-based molecules, marking a breakthrough in the quest to understand and enhance the physical properties of these promising materials. The work is published in the Journal of the American Chemical Society.
A new study uncovers revealing insights into how plastic materials used in electronics are formed, and how hidden flaws in their structure could be limiting their performance.
Conjugated polymers are a type of plastic that conduct electricity and are used in optoelectronics, computing, biosensors, and power generation. The materials are lightweight, low-cost, and can be printed in thin layers onto flexible substrates, making them ideal for next-generation technologies.
An international team of scientists investigated a popular method for making the polymers called aldol condensation, which is praised for being versatile, metal-free, environmentally friendly, and scalable.
Researchers at Northeastern University have discovered how to change the electronic state of matter on demand, a breakthrough that could make electronics 1,000 times faster and more efficient.
By switching from insulating to conducting and vice versa, the discovery creates the potential to replace silicon components in electronics with exponentially smaller and faster quantum materials.
“Processors work in gigahertz right now,” said Alberto de la Torre, assistant professor of physics and lead author of the research. “The speed of change that this would enable would allow you to go to terahertz.”
Northeastern researchers discovered how to control quantum materials with light, potentially making electronics 1,000 times faster.
Dr. Jung-Dae Kwon’s research team at the Energy & Environmental Materials Research Division of the Korea Institute of Materials Science (KIMS) has successfully developed an amorphous silicon optoelectronic device with minimal defects, even using a low-temperature process at 90°C. The findings are published in the journal Advanced Science.
Notably, the team overcame the limitations of high-temperature processing by precisely controlling the hydrogen dilution ratio—the ratio of hydrogen to silane (SiH4) gas—enabling the fabrication of high-performance flexible optoelectronic devices (sensors that detect light and convert it into electrical signals).
Flexible optoelectronic devices are key components of next-generation electronic devices, such as wearable electronics and image sensors, and require the precise deposition of thin films on thin, bendable substrates. However, a major limitation has been the necessity of high-temperature processing above 250°C, making it difficult to apply these devices to heat-sensitive flexible substrates.
In crystalline materials, the fabrication of optical waveguides by femtosecond laser irradiation is not as easy as in glasses [7] because, in many cases, it is not possible to produce a refractive index increase, able to directly confine and guide light along a certain trajectory. On the contrary, the most typical situation is that the refractive index of the crystal is decreased by the effect of the high intensity of the laser, but even in those cases it can be used anyway to design efficient waveguides [22].
In our study, we designed and fabricated waveguides with different configurations and geometries in the search for the best performance, helping us to understand the confinement mechanisms in Pr: LLF. The following waveguide types were tested:
Nematic materials are made of elongated molecules that align in a preferred direction, but, like in a fluid, are spaced out irregularly. The best-known nematic materials are liquid crystals, which are used in liquid crystal display (LCD) screens. However, nematic order has been identified in a wide range of systems, including bacterial suspensions and superconductors.
Now, a team led by researchers at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), SLAC National Accelerator Laboratory and University of California, Santa Cruz, has discovered a nematic order in a magnetic material, in which the magnetic spins of the material are arranged into coils pointing in the same general direction.
“If we think of these magnetic helices as the objects that are aligning, the magnetism follows expectations for nematic phases,” said Zoey Tumbleson, a graduate student at Berkeley Lab and the University of California, Santa Cruz, who led this work. “These phases were not previously known and it’s very exciting to see this generalized to a wider field of study.”
Scientists have discovered a new way that matter can exist—one that is different from the usual states of solid, liquid, gas or plasma—at the interface of two exotic materials made into a sandwich.
The new quantum state, called quantum liquid crystal, appears to follow its own rules and offers characteristics that could pave the way for advanced technological applications, the scientists said.
In an article published in the journal Science Advances, a Rutgers-led team of researchers described an experiment that focused on the interaction between a conducting material called the Weyl semimetal and an insulating magnetic material known as spin ice when both are subjected to an extremely high magnetic field. Both materials individually are known for their unique and complex properties.
Using ultrafast x-ray pulses, researchers have probed the chirality of spin spirals in synthetic antiferromagnets.
Magnetism is a constant companion in our daily lives. Data storage, sensors, electric motors—none of these devices would function without it. Yet most technologies exploit only the simplest form of magnetic order: ferromagnetism, in which all magnetic moments within a domain align in the same direction. But magnetic order can be far more intricate. In conventional antiferromagnets (AFMs), the magnetic moments align in opposite directions to produce zero net magnetization, a type of order which has several advantages over ferromagnetism in many next-generation technological applications. In more exotic materials, the magnetic moments can twist into spirals, vortices, and other spin structures that might one day be used to store information. Occurring in both ferromagnets and AFMs, these spin structures are defined by their chirality, the direction in which the spins rotate relative to a fixed axis.
The chirality is a key fingerprint of the competing interactions at play in complex magnetic systems. However, observing the dynamics of chirality and magnetization in AFMs has been experimentally challenging, as both can evolve over nanometer length scales and on femtosecond timescales. In a new study, Zongxia Guo from the French National Centre for Scientific Research and colleagues have taken a major step forward by probing both quantities with ultrashort and ultrabright pulses from a free-electron laser (FEL) [1]. The researchers look specifically at spin spirals in an AFM, and they find that—under laser excitation—the chirality and magnetization evolve together in near unison and on significantly faster time scales than is observed for ferromagnets. Such fast spin dynamics in chiral spin structures offers a promising new route for how we will store, transfer, and compute information in the future.
The time delay experienced by a scattered light signal has an imaginary part that was considered unobservable, but researchers have isolated its effect in a frequency shift.
A scattering material, such as a frosted window or a thin fog, will cause light to travel slower than it would if no material were in its path. The mathematical formula for this time delay has a real part—which is well studied—and a lesser-known imaginary part. “The imaginary time delay has been largely ignored and disregarded as unphysical,” says Isabella Giovannelli from the University of Maryland. But she and her advisor Steven Anlage have now measured this abstract quantity by recording a corresponding frequency shift in scattered light pulses [1].
The real part of the time delay has been observed in many experiments, particularly slow-light setups where light pulses can become effectively trapped inside a scattering medium (see Focus: Light Nearly Stopped in a Waveguide). By contrast, the imaginary part has been stuck in the realm of mathematics. Theoretical work from 2016, however, showed that the imaginary time delay can be related to a potentially observable frequency shift [2].
New research by scientists from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), in collaboration with scientists from TAU Systems Inc., has brought the promise of smaller and more affordable X-ray free-electron lasers one step closer to reality.
X-ray free-electron lasers (XFELs) are powerful light sources and are typically large research instruments. Scientists use them to probe nature’s secrets at the atomic level, enabling advances in medicine, biology, physics, materials, and more. The push to develop more compact and less expensive XFELs is expected to increase the number of facilities that will be able to implement this technology, greatly expanding its impact across many areas of science.
“As part of this effort, we are applying our long-standing expertise in a type of advanced accelerator called laser plasma acceleration to shrink XFELs,” said Sam Barber, a staff scientist in Berkeley Lab’s Accelerator Technology & Applied Physics (ATAP) Division. “In addition to standalone light sources, exceptionally high-quality electron beams from plasma accelerators could be injected into existing XFELs to significantly extend their performance.”