Research / Technical - Page 11

Scientists from MIT, Arizona State University, National Institute for Materials Science in Tsukuba, Université de Liège in Belgium and Italy's CNR-SPIN have discovered an exotic "multiferroic" state in a material that is as thin as a single layer of atoms.

Their observation is the first to confirm that multiferroic properties can exist in a perfectly two-dimensional material. The findings could pave the way for developing smaller, faster, and more efficient data-storage devices built with ultrathin multiferroic bits, as well as other new nanoscale structures.

Researchers at The University of Manchester and Japan's National Institute for Materials Science seem to have made a significant step towards quantum computing, demonstrating step-change improvements in the spin transport characteristics of nanoscale graphene-based electronic devices.

The team used monolayer graphene encapsulated by another 2D material (hexagonal boron nitride) in a so-called van der Waals heterostructure with one-dimensional contacts. This architecture was reported to deliver an extremely high-quality graphene channel, reducing the interference or electronic ‘doping’ by traditional 2D tunnel contacts.

An international collaboration involving the Irradiated Solids Laboratory at EPFL has published a paper detailing the mechanisms for detecting circularly polarized light using spin-optoelectronic devices called spin photodiodes.

"In this work, we combined spintronics with optics. This is spin-optoelectronics," explains Henri-Jean Drouhin, co-author of the study published and head of the 'Physics and Chemistry of Nano-objects' group at the Irradiated Solids Laboratory (LSI). Light particles, photons, also have a spin. This spin manifests itself in the fact that light can be right- or left-handed circularly polarized (which means that the electric field of the light winds to the right or left like a helix in the direction of propagation of the photons). When this light hits the device designed by the researchers, photons can excite electrons in the material. The spin of these electrons then adopts a preferential direction that depends on the photon spin. Knowing how to selectively extract the electrons therefore makes it possible to obtain information on the polarization of the incident light, making these devices 'spin photodiodes', in contrast to conventional photodiodes that measure the intensity of the light.

Researchers from Japan Advanced Institute of Science and Technology (JAIST), Kyoto University and the National Institute for Materials Science in Japan have detected energetic magnons in yttrium iron garnet (YIG), a magnetic insulator, by using a quantum sensor based on diamond with NV centers.

Nitrogen-vacancy (N-V) centers in diamond, basically a point defect consisting of a nitrogen atom paired with an adjacent lattice vacancy, have emerged as a key for high-resolution quantum sensors. It has been demonstrated that N-V centers can detect coherent magnon. However, detecting the thermally excited magnons by heat using N-V centers is difficult since the thermal magnons have much higher energy than the spin state of N-V centers, limiting their interaction.

An international team of researchers, led by the National Research Council (CNR), IOM institute in Trieste, Italy, and the Departments of Chemistry at Princeton University, Louisiana State University and Rutgers University in United States, has relied in a joint venture between theorists, experimentalists and sample growers across chemistry and physics to study the magnetic and electronic properties of EuSn₂P₂, a magnetic topological insulator composed of Europium, Tin, and Phosphorus arranged in a layer-by-layer crystalline structure.

The understanding and the interplay of magnetism and high-order topology in a quantum material is one of the most challenging research directions in materials science, holding potentialities for future spintronics applications, where the spin carried by an electron, being an essential quantum entity, could be manipulated and used as information carrier in a device and/or as a single quantum bit of information.

A research team from Brown University has found a surprising new phenomenon that can arise in 'magic-angle graphene' - two sheets of graphene that are stacked together at a particular angle with respect to each other, giving rise to various fascinating behaviors. In a recent research, the team showed that by inducing a phenomenon known as spin-orbit coupling, magic-angle graphene becomes a powerful ferromagnet.

"Magnetism and superconductivity are usually at opposite ends of the spectrum in condensed matter physics, and it's rare for them to appear in the same material platform," said Jia Li, an assistant professor of physics at Brown and senior author of the research. "Yet we've shown that we can create magnetism in a system that originally hosts superconductivity. This gives us a new way to study the interplay between superconductivity and magnetism, and provides exciting new possibilities for quantum science research."

Researchers at Tokyo Institute of Technology, the University of Tokyo, Japan Science and Technology Agency (JST), RIKEN and Comprehensive Research Organization for Science and Society (CROSS) have demonstrated a large, unconventional anomalous Hall resistance in a new magnetic semiconductor in the absence of large-scale magnetic ordering.

This validates a recent theoretical prediction and provides new insights into the anomalous Hall effect, a quantum phenomenon that has previously been associated with long-range magnetic order.

Researchers from Harvard University and Japan's National Institute for Materials Science have demonstrated a new way to measure the properties of spin waves in graphene.

A charge sensor measuring the cost of electrons surfing on the spin wave (green wavy lines) (Credit: Yacoby Lab/ Harvard SEAS)

Spin waves, a change in electron spin that propagates through a material, could fundamentally change how devices store and carry information. These waves, also known as magnons, don’t scatter or couple with other particles. Under the right conditions, they can even act like a superfluid, moving through a material with zero energy loss.

Researchers at Tohoku University and the University of Gothenburg have designed a new spintronics technology for brain-inspired computing.

Sophisticated cognitive tasks, such as image and speech recognition, have seen recent breakthroughs thanks to deep learning. Even so, the human brain still executes these tasks without exerting much energy and with greater efficiency than any computer. The development of energy-efficient artificial neurons capable of emulating brain-inspired processes has therefore been a major research goal for decades.

An international team has, for the first time, designed a material system that exhibits an unusually long-range Josephson effect. Regions of superconducting YBa₂Cu₃O₇ are separated by a region of half-metallic, ferromagnetic manganite (La₂/₃Sr₁/₃MnO₃) one micron wide.

When two superconducting regions are separated by a strip of non-superconducting material, a special quantum effect can occur, coupling both regions. This is known as the Josephson effect. If the spacer material is a half-metal ferromagnet, it can open up new potential applications for novel spintronic applications.