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In a new study, U.S. and Austrian physicists have observed quantum entanglement among “billions of billions” of flowing electrons in a quantum critical material.

The research, which appears this week in Science, examined the electronic and magnetic behavior of a “strange metal” compound of ytterbium, rhodium and silicon as it both neared and passed through a critical transition at the boundary between two well-studied quantum phases.

The study at Rice University and Vienna University of Technology (TU Wien) provides the strongest direct evidence to date of entanglement’s role in bringing about quantum criticality, said study co-author Qimiao Si of Rice.

Composites made from self-assembling inorganic materials are valued for their unique strength and thermal, optical and magnetic properties. However, because self-assembly can be difficult to control, the structures formed can be highly disordered, leading to defects during large-scale production. Researchers at the University of Illinois and the University of Michigan have developed a templating technique that instills greater order and gives rise to new 3D structures in a special class of materials, called eutectics, to form new, high-performance materials.

The findings of the collaborative study are published in the journal Nature.

Eutectic materials contain elements and compounds that have different melting and solidification temperatures. When combined, however, the composite formed has single melting and freezing temperatures—like when salt and water combined to form brine, which freezes at a lower temperature than water or salt alone, the researchers said. When a eutectic liquid solidifies, the individual components separate, forming a cohesive structure—most commonly in a layered form. The fact that eutectic materials self-assemble into composites makes them highly desirable to many modern technologies, ranging from high-performance turbine blades to solder alloys.

Use of an AC rather than a DC electric field can improve the piezoelectric response of a crystal. Now, an international team of researchers say that cycles of AC fields also make the internal crystal domains in some materials bigger and the crystal transparent.

“There have been reports that the use of AC fields could significantly improve the piezoelectric responses—for example by 20% to 40%—over DC fields and the improvements have always been attributed to the smaller internal ferroelectric domain sizes that resulted from the cycles of AC fields,” said Long-Qing Chen, Hamer Professor of Materials Science and Engineering, professor of engineering science and mechanics, and professor of mathematics at Penn State. “About three years ago, Dr. Fei Li, then a research associate at the Materials Research Institute at Penn State, largely confirmed the improvement of piezoelectric performances from application of AC fields. However, it was not clear at all how the internal ferroelectric domains evolved during AC cycles.

”Our group does mostly computer modeling, and more than a year ago we started looking into what happens to the internal domain structures if we apply AC fields to a ferroelectric piezoelectric crystal. We are very curious about how the domain structures evolve during AC cycles. Our computer simulations and theoretical calculations did show an improved piezoelectric response, but our simulations also demonstrated that the ferroelectric domain sizes actually got bigger during AC cycles rather than smaller as reported in the literature.”

Homeland Security might soon have a new tool to add to its arsenal.

Researchers at Northwestern University and Argonne National Laboratory have developed a new material that opens doors for a new class of neutron detectors.

With the ability to sense smuggled nuclear materials, highly efficient neutron detectors are critical for national security. Currently, there are two classes of detectors which either use helium gas or flashes of light. These detectors are very large—sometimes the size of a wall.

FSJs (Ferroelectric Semiconductor Junction) in neuromorphic chips.

Engineers at Purdue University and at Georgia Tech have constructed the first devices from a new kind of two-dimensional material that combines memory-retaining properties and semiconductor properties. The engineers used a newly discovered ferroelectric semiconductor, alpha indium selenide, in two applications: as the basis of a type of transistor that stores memory as the amount of amplification it produces; and in a two-terminal device that could act as a component in future brain-inspired computers. The latter device was unveiled last month at the IEEE International Electron Devices Meeting in San Francisco.

Ferroelectric materials become polarized in an electric field and retain that polarization even after the field has been removed. Ferroelectric RAM cells in commercial memory chips use the former ability to store data in a capacitor-like structure. Recently, researchers have been trying to coax more tricks from these ferroelectric materials by bringing them into the transistor structure itself or by building other types of devices from them.

Continue reading “Ferroelectric Semiconductors Could Mix Memory and Logic” »

Launching in late 2021, Lucy will be the first space mission to explore the Trojan asteroids. These are a population of small bodies that are left over from the formation of the solar system. They lead or follow Jupiter in their orbit around the Sun, and they may tell us about the origins of organic materials on Earth.

Lucy will fly by and carry out remote sensing on six different Trojan asteroids and will study surface geology, surface color and composition, asteroid interiors/bulk properties, and will look at the satellites and rings of the Trojans.

A team of physicists has mapped how electron energies vary from region to region in a particular quantum state with unprecedented clarity. This understanding reveals an underlying mechanism by which electrons influence one another, termed quantum “hybridization,” that had been invisible in previous experiments.

The findings, the work of scientists at New York University, the Lawrence Berkeley National Laboratory, Rutgers University, and MIT, are reported in the journal Nature Physics.

“This sort of relationship is essential to understanding a quantum electron system—and the foundation of all movement—but had often been studied from a theoretical standpoint and not thought of as observable through experiments,” explains Andrew Wray, an assistant professor in NYU’s Department of Physics and one of the paper’s co-authors. “Remarkably, this work reveals a diversity of energetic environments inside the same material, allowing for comparisons that let us spot how electrons shift between states.”

ETH researchers have created an incredibly lightweight 18-carat gold, using a matrix of plastic in place of metallic alloy elements.

Uranium contaminated groundwater that is unsafe to drink could be cleaned up using the new remediation technique.

An electrochemical technique could prevent the spread of uranium in contaminated groundwater and provide a new way to source material for use in nuclear fuel.