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Category: materials – Page 8

Northeastern discovery in quantum materials could make electronics 1,000 times faster

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.

Flexible optoelectronic device with minimal defects fabricated at just 90°C

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 ).

Flexible optoelectronic devices are key components of next-generation , 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.

Comparative Performance Analysis of Femtosecond-Laser-Written Diode-Pumped Pr: LiLuF4 Visible Waveguide Lasers

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:

Researchers observe nematic order in magnetic helices, echoing liquid crystal behavior

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 , 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.”

New quantum state of matter found at interface of exotic materials

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.

Let’s Twist Again: Seeing Spin Spirals in Action

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.

Imaginary Time Delays Are For Real

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].

Researchers make key gains in unlocking the promise of compact X-ray free-electron lasers

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.”

Cost effective method developed for co-packaging photonic and electronic chips

The future of digital computing and communications will involve both electronics—manipulating data with electricity—and photonics, or doing the same with light. Together the two could allow exponentially more data traffic across the globe in a process that is also more energy efficient.

“The bottom line is that integrating photonics with electronics in the same package is the transistor for the 21st century. If we can’t figure out how to do that, then we’re not going to be able to scale forward,” says Lionel Kimerling, the Thomas Lord Professor of Materials Science and Engineering at MIT and director of the MIT Microphotonics Center.

Enter FUTUR-IC, a new research team based at MIT. “Our goal is to build a microchip industry value chain that is resource-efficient,” says Anu Agarwal, head of FUTUR-IC and a principal research scientist at the Materials Research Laboratory (MRL).

AI-designed 3D materials enable custom control over how light bends

Refraction—the bending of light as it passes through different media—has long been constrained by physical laws that prevent independent control over how light waves along different directions bend. Now, UCLA researchers have developed a new class of passive materials that can be structurally engineered to “program” refraction, enabling arbitrary control over the bending of light waves.

In a study published in Nature Communications, a team led by Dr. Aydogan Ozcan, the Chancellor’s Professor of Electrical & Computer Engineering at UCLA, has introduced a called a refractive function generator (RFG) that can independently tailor the output direction of refracted light for each input direction. This device allows light to be steered, filtered, or redirected according to custom-designed rules—far beyond what standard materials or traditional metasurfaces can achieve.

Standard refraction, described by Snell’s law, links the input and output directions of light using fixed material properties. Even advanced metasurface designs only allow limited tunability of refraction.

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