#atomic scale

New Post has been published on https://thedigitalinsider.com/new-quantum-entangled-material-could-pave-way-for-ultrathin-quantum-technologies-technology-org/

New quantum entangled material could pave way for ultrathin quantum technologies - Technology Org

Two-dimensional quantum materials provide a unique platform for new quantum technologies, because they offer the flexibility of combining different monolayers featuring radically distinct quantum states. Different two-dimensional materials can provide building blocks with features like superconductivity, magnetism, and topological matter. But so far, creating a monolayer of heavy-fermion Kondo matter – a state of matter dominated by quantum entanglement – has eluded scientists. Now, researchers at Aalto University have shown that it’s theoretically possible for heavy-fermion Kondo matter to appear in a monolayer material, and they’ve described the microscopic interactions that produces its unconventional behavior. These findings were published in Nano Letters.

Artistic illustration depicts heavy-fermion Kondo matter in a monolayer material. Image Credit: Adolfo Fumega/Aalto University

“Heavy-fermion materials are promising candidates to discover unconventional topological superconductivity, a potential building block for quantum computers robust to noise,” says Adolfo Fumega, the first author of the paper and a post-doctoral researcher at Aalto University.

These materials can feature two phases: one analogous to a conventional magnet, and one where the state of the system is dominated by quantum entanglement, known as the heavy-fermion Kondo state. At the transition between the magnetic phase and the heavy-fermion state, macroscopic quantum fluctuations appear, leading to exotic states of matter including unconventional superconducting phases.

Traditionally, heavy-fermion compounds have been studied in bulk materials. Previous investigations carried at Aalto University by the Atomic Scale Physics and Correlated Quantum Materials groups provided the first theoretical and experimental demonstrations of heavy-fermion Kondo matter in van der Waals heterostructures. Two of these papers were published in Nature and Physical Review Letters in 2021.

However, an intrinsic heavy-fermion state in a van der Waals monolayer has remained elusive. Layered van der Waals materials offer new degrees of freedom such as stacking of different layers to engineer heterostructures, twisting the layers to create moiré patterns or applying electric gate voltages, strategies allowing to explore and engineer the different phases of heavy-fermion materials in a controlled way.

The monolayer material researchers analyzed is monolayer CeSiI, a compound that has been recently isolated in the ultrathin limit. Using a combination of many-body and quantum chemistry methods, they showed the nature of competing quantum magnetic interactions in the material, demonstrating that such competition leads to an unconventional quantum entangled state. Furthermore, they showed that the quantum magnetism in this material is dominated by relativistic effects, leading to a subatomic magnetic structure radically different from other two-dimensional materials.

“The discovery of a heavy-fermion quantum material monolayer establishes a fundamental building block for quantum devices,” says Jose Lado, an assistant professor at Aalto University who also heads the Correlated Quantum Materials research group.

Bulk heavy-fermion materials are greatly challenging from the material science point of view, and making devices out of them is a nearly impossible task. With a purely two-dimensional heavy-fermion quantum material and the flexibility of stacking van der Waals layers, a whole new family of quantum devices based on exotic heavy-fermion Kondo phenomena may be developed, opening up yet unexplored directions in quantum technologies.

Source: Aalto University

New Post has been published on https://thedigitalinsider.com/nano-droplets-go-skiing-at-high-temperatures-technology-org/

Nano Droplets Go Skiing at High Temperatures - Technology Org

Currently, many (nano)structures including nano droplets are grown in layers, one above the other, but their ordering on the atomic scale is generally far from perfect.  

The researchers aim for a better understanding of these processes that can eventually lead to smaller, faster and overall better nanotechnology and have, in a worldwide first observation, discovered pre-solidification in droplet mixture. They recently published these exciting findings in the scientific journal Physical Review Letters.

Chemistry, droplets – illustrative rendering. Image credit: Pixabay (Free Pixabay license)

The droplets are composed of a mixture of the metals platinum and germanium and move on a heated substrate in the direction of the heat source. But as soon as the temperature lowers, the droplets start their unique behaviour.

Like professional skiers, they suddenly change their direction and make a slalom. “Using a photo-emission electron microscope, we were able to film the skiing and show the whole process of solidifying”, explains Arie van Houselt, corresponding author of the publication.

Skiing act unlike any other

The skiing droplets form at surprisingly high temperatures. “This happens at ninety degrees above their eutectic point, which is the temperature at which these types of mixtures freeze. The droplets don’t solidify all at once. They first elongate and then the solidifying process starts at the bottom. On their interface with the substrate”, explains Van Houselt.

This first solid layer also explains the skiing. When the material solidifies, it gains a nanostructure which acts as a grid on which the droplet can move. The nanostructure lowers the resistance of the droplets in another direction. The droplets make use of this lowered resistance and make a sharp turn. They start moving in this direction.

Arie van Houselt. Image credit: University of Twente

Invaluable insights

This remarkable display isn’t just an entertaining performance at the nanoscale. The conditions under which these droplets display their extraordinary skiing are close to those found in the growth of many (nano)structures, such as nanowires and germanene.

Van Houselt said: “Discoveries like this one provide invaluable insights into the mechanisms of these transformations, potentially opening the doors to the creation of flawlessly engineered computer chips.”

More information

New Post has been published on https://thedigitalinsider.com/world-class-neutron-source-takes-a-break-for-major-proton-power-upgrade-technology-org/

World-class Neutron Source Takes a Break for Major Proton Power Upgrade - Technology Org

The Spallation Neutron Source at Oak Ridge National Laboratory — already the world’s most powerful accelerator-based neutron source — will be on a planned hiatus through June 2024 as crews work to upgrade the facility.

The Spallation Neutron Source. Image credit: ORNL

Much of the work — part of the facility’s Proton Power Upgrade project — will involve building a connector between the accelerator and the planned Second Target Station at SNS. When complete, the PPU project will bring the accelerator up to 2.8 megawatts from its current record-breaking 1.7 megawatts of beam power.

Workers will add about 3,000 square feet of concrete tunnel, the “stub,” which will integrate with an existing tunnel. Construction tasks include associated structures, roofing, geomembrane liner, tunnel waterproofing, electrical, fire alarm, ventilation systems and controls.

“The construction crews have performed all of the excavation work and are transitioning to tunnel base and wall construction,” said ORNL’s Mark Champion, PPU project manager.

The stub is scheduled to be completed within six months, by the end of February, and most of the rest of this outage will involve installing new components and systems to complete the PPU project.

That work includes:

Installing three new cryomodules, adding more radio-frequency stations and upgrading two high-voltage units to support new 3.0 megawatt klystrons.

Installing an injection dump imaging system and new magnets and upgrading deionized water systems, power supplies and a beam power limit system.

Installing a new liquid hydrogen refill system, mercury overflow tank and target complete with gas injection and recirculation system.

Completing controls integration.

The upgrade will increase the flow of neutrons — known as the neutron flux — to the First Target Station, or FTS, and eventually also power the STS.

The Spallation Neutron Source. Image credit: ORNL

Power to the FTS — which produces thermal neutrons to analyze samples down to the atomic scale — will increase to 2.0 megawatts, enabling new scientific discoveries in such areas as superconductors, energy materials such as those used in batteries, and basic physics.

The additional power will be split via the stub, to power the STS, which will have the world’s highest peak brightness of neutrons, tailored for probing soft matter such as polymers and biological materials, and complex engineering materials. This is used in vaccine research, advanced batteries and for decarbonization studies.

“It’s very gratifying to reach one of the final stages of the project after several years of planning, design and engineering,” said ORNL’s John Galambos, PPU project director.

“It’s a huge tribute to the skills and dedication of the entire PPU team and our partner labs that the project has remained on schedule and on budget despite unprecedented challenges, including Covid-19 and subsequent supply chain issues.”

The Spallation Neutron Source is an Office of Science user facility at ORNL.

UT-Battelle manages ORNL for the Department of Energy’s Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science.

Source: Oak Ridge National Laboratory

Watch: First-ever recording of a pair of atoms forming, breaking chemical bonds- Technology News, Firstpost

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tech2 News StaffFeb 04, 2020 10:26:13 IST

Atoms make up everything in the physical world, and yet, it’s been only possible to see images and theories about how atoms really look. If they didn’t build bonds and connect to each another, nothing we know of in the universe would exist — be it the Sun, our planet or the 8 billion+ forms of life that inhabit it.

All matter in the known…

Where the (re)action is

To really understand something you usually have to get out that fine-toothed comb and get into the details. What happens in the nitty-gritty can dictate how big systems function.

So a new way of seeing what’s really happening when solids and liquids meet - the chemical reactions occurring at that intersection - could bring important new insights to bear on many challenges, such as water purification or making better batteries.