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In a new study, a group of researchers led by Prof. Lior Klein, from the physics department and the Institute of Nanotechnology and Advanced Materials at Bar-Ilan University, has shown that relatively simple structures can support an exponential number of magnetic states—much greater than previously thought. They have additionally demonstrated switching between the states by generating spin currents. Their results may pave the way to multi-level magnetic memory with an extremely large number of states per cell; it could also have application in the development of neuromorphic computing, and more. Their research appears as a featured article on the cover of a June issue of Applied Physics Letters.

Spintronics is a thriving branch of nano-electronics which uses the spin of the electron and its associated magnetic moment in addition to the electron charge used in traditional electronics. The main practical contributions of spintronics are in magnetic sensing and non-volatile magnetic data storage, and researchers are pursuing breakthroughs in developing magnetic-based processing and novel types of magnetic memory.

Spintronics devices commonly consist of magnetic elements manipulated by spin-polarized currents between stable magnetic states. When spintronic devices are used for storing data, the number of stable states sets an upper limit on memory capacity. While current commercial magnetic memory cells have two stable magnetic states corresponding to two memory states, there are clear advantages to increasing this number, as it will potentially allow increasing memory density and enable the design of novel types of memory.

Rigid electromagnetic actuators have a variety of applications, but their bulky nature limits human-actuator integration or machine-human collaborations. In a new report on Science Advances, Guoyong Mao and a team of scientists in soft matter physics and soft materials at the Johannes Kepler University Linz, Austria, introduced soft electromagnetic actuators (SEMAs) to replace solid metal coils with liquid-metal channels embedded in elastomeric shells. The scientists demonstrated the user-friendly, simple and stretchable construct with fast and durable programmability.

They engineered a SEMA based soft miniature shark and a multi-coil flower with individually controlled petals, as well as a cubic SEMA to perform arbitrary motion sequences. The team adapted a numerical model to support device miniaturization and reduce power consumption with increased mechanical efficiency. The SEMAs are electrically controlled shape-memory systems with applications to empower soft grippers for minimally invasive medical applications. The scientists highlighted the practicality of small size and multi-coil SEMAs for promising applications in medicine, much like in the classic sci-fi movie “Fantastic Voyage,” in which a miniature submarine destroyed a blood clot to save a patient’s life. In reality, Mao et al. aim to develop and deploy SEMA-based advanced microrobots for such futuristic medical applications, including drug delivery and tissue diagnostics with nano-precision.

While so many of us are working at home during the coronavirus pandemic, we do worry that serendipitous hallway conversations aren’t happening.

Last year, before the pandemic, it was one of those conversations that led researchers at ETH Zurich to develop a way of making chocolates shimmer with color—without any coloring agents or other additives.

The project, announced in December, involves what the scientists call “structural color”. The team indicated that it creates colors in a way similar to what a chameleon does—that is, using the structure of its skin to scatter a particular wavelength of light. The researchers have yet to release details, but Alissa M. Fitzgerald, founder of MEMS product development firm AMFitzgerald, has a pretty good guess.

The rapid development of renewable energy resources has triggered tremendous demands in large-scale, cost-efficient and high-energy-density stationary energy storage systems.

Lithium ion batteries (LIBs) have many advantages but there are much more abundant metallic elements available such as sodium, potassium, zinc and aluminum.

These elements have similar chemistries to lithium and have recently been extensively investigated, including sodium-ion batteries (SIBs), potassium-ion batteries (PIBs), zinc-ion batteries (ZIBs), and aluminum-ion batteries (AIBs). Despite promising aspects relating to redox potential and energy density the development of these beyond-LIBs has been impeded by the lack of suitable electrode materials.

Scientists at the University of Tsukuba use computer calculations to propose a new way to rearrange the carbon atoms in a diamond to make it even harder, which may be useful in industrial applications that rely on synthetic cutting diamonds.

Researchers at the University of Tsukuba used computer calculations to design a new carbon-based material even harder than diamond. This structure, dubbed “pentadiamond” by its creators, may be useful for replacing current synthetic diamonds in difficult cutting manufacturing tasks.

Diamonds, which are made entirely of carbon atoms arranged in a dense lattice, are famous for their unmatched hardness among known materials. However, carbon can form many other stable configurations, called allotropes. These include the familiar graphite in pencil lead, as well as nanomaterials such as carbon nanotubes. The mechanical properties, including hardness, of an allotrope depend mostly on the way its atoms bond with each other. In conventional diamonds, each carbon atom forms a covalent bond with four neighbors. Chemists call carbon atoms like this as having sp³ hybridization. In nanotubes and some other materials, each carbon forms three bonds, called sp² hybridization.

Bright, iridescent colors observed in nature are often caused by light interference within nanoscale periodic lattices, inspiring numerous strategies for coloration devoid of inorganic pigments. Here, we describe and characterize the septum of the Lunaria annua plant that generates large (multicentimeter), freestanding iridescent sheets, with distinctive silvery-white reflective appearance. This originates from the thin-film assembly of cellulose fibers in the cells of the septum that induce thin-film interference–like colors at the microscale, thus accounting for the structure’s overall silvery-white reflectance at the macroscale. These cells further assemble into two thin layers, resulting in a mechanically robust, iridescent septum, which is also significantly light due to its high air porosity (70%) arising from the cells’ hollow-core structure. This combination of hierarchical structure comprising mechanical and optical function can inspire technological classes of devices and interfaces based on robust, light, and spectrally responsive natural substrates.

Structural color has captured the fascination of optical researchers through numerous observations throughout history, both in naturally occurring structures and in the animal world (1–3). Plants have also evolved structural colors to fulfill a variety of functions (4–7): Structurally colored leaves (8–10), flowers (11, 12), and fruits (4, 5, 13, 14) are used by plants to regulate light harvesting (8, 15–17) and attract pollinators (6, 7), while they are also believed to promote seed dispersal (4, 5). The few, so far, described plants whose fruits are structurally colored are understory species living in tropical regions, whose fruits reflect light spanning from deep metallic blue to green when ripe.

A team of researchers from the Technion – Israel Institute of Technology has observed branched flow of light for the very first time. The findings are published in Nature and are featured on the cover of the July 2, 2020 issue.

The study was carried out by Ph.D. student Anatoly (Tolik) Patsyk, in collaboration with Miguel A. Bandres, who was a postdoctoral fellow at Technion when the project started and is now an Assistant Professor at CREOL, College of Optics and Photonics, University of Central Florida. The research was led by Technion President Professor Uri Sivan and Distinguished Professor Mordechai (Moti) Segev of the Technion’s Physics and Electrical Engineering Faculties, the Solid State Institute, and the Russell Berrie Nanotechnology Institute.

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Research at IIT-Istituto Italiano di Tecnologia (Italian Institute of Technology) has led to the revolutionary development of an artificial liquid retinal prosthesis to counteract the effects of diseases such as retinitis pigmentosa and age-related macular degeneration that cause the progressive degeneration of photoreceptors of the retina, resulting in blindness. The study has been published in Nature Nanotechnology.

The study represents the state of the art in retinal prosthetics and is an evolution of the planar artificial retinal model developed by the same team in 2017 and based on organic semiconductor materials (Nature Materials 2017, 16: 681–689).

The ‘second generation’ artificial retina is biomimetic, offers high spatial resolution and consists of an aqueous component in which photoactive polymeric nanoparticles (whose size is 350 nanometres, thus about 1/100 of the diameter of a hair) are suspended, and will replace damaged photoreceptors.

Graphene’s unique 2-D structure means that electrons travel through it differently than in most other materials. One consequence of this unique transport is that applying a voltage doesn’t stop the electrons like it does in most other materials. This is a problem, because to make useful applications out of graphene and its unique electrons, such as quantum computers, it is necessary to be able to stop and control graphene electrons.

An interdisciplinary team of scientists from the Universidad Autonoma de Madrid (Spain), Université Grenoble Alpes (France), International Iberian Nanotechnology Laboratory (Portugal) and Aalto University has solved this long-standing problem. The team included experimental researchers Eva Cortés del Río, Pierre Mallet, Héctor González‐Herrero, José María Gómez‐Rodríguez, Jean‐Yves Veuillen and Iván Brihuega and theorists including Joaquín Fernández-Rossier and Jose Lado, assistant professor in the department of Applied Physics at Aalto.

The experimental team used atomic bricks to build walls capable of stopping the graphene electrons. This was achieved by creating atomic walls that confined the electrons, leading to structures whose spectrum was then compared with theoretical predictions, demonstrating that electrons were confined. In particular, it was obtained that the engineered structures gave rise to nearly perfect confinement of electrons, as demonstrated from the emergence of sharp quantum well resonances with a remarkably long lifetime.