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Graphene and 2D materials could move electronics beyond ‘Moore’s Law’

A team of researchers based in Manchester, the Netherlands, Singapore, Spain, Switzerland and the USA has published a new review on a field of computer device development known as spintronics, which could see graphene used as building block for next-generation electronics.

Recent theoretical and experimental advances and phenomena in studies of electronic spin transport in graphene and related two-dimensional (2D) materials have emerged as a fascinating area of research and development.

Spintronics is the combination of electronics and magnetism, at the nanoscale and could lead to next generation high-speed electronics. Spintronic devices are a viable alternative for nanoelectronics beyond Moore’s law, offering higher energy efficiency and lower dissipation as compared to conventional electronics, which relies on charge currents. In principle we could have phones and tablets operating with spin-based transistors and memories.

As published in APS Journal Review of Modern Physics, the review focuses on the new perspectives provided by heterostructures and their emergent phenomena, including proximity-enabled spin-orbit effects, coupling spin to light, electrical tunability and 2D magnetism.

The average person already encounters spintronics in laptops and PCs, which are already using spintronics in the form of the magnetic sensors in the reading heads of hard disk drives. These sensors are also used in the automotive industry.

Spintronics is a new approach to developing electronics where both memory devices (RAM) and logic devices (transistors) are implemented with the use of ‘spin’, which is the basic property of electrons that cause them to behave like tiny magnets, as well as the electronic charge.

Dr Ivan Vera Marun, Lecturer in Condensed Matter Physics at The University of Manchester said: “The continuous progress in graphene spintronics, and more broadly in 2D heterostructures, has resulted in the efficient creation, transport, and detection of spin information using effects previously inaccessible to graphene alone.

“As efforts on both the fundamental and technological aspects continue, we believe that ballistic spin transport will be realised in 2D heterostructures, even at room temperature. Such transport would enable practical use of the quantum mechanical properties of electron wave functions, bringing spins in 2D materials to the service of future quantum computation approaches.”

Controlled spin transport in graphene and other two-dimensional materials has become increasingly promising for applications in devices. Of particular interest are custom-tailored heterostructures, known as van der Waals heterostructures, that consist of stacks of two-dimensional materials in a precisely controlled order. This review gives an overview of this developing field of graphene spintronics and outlines the experimental and theoretical state of the art.

Billions of spintronics devices such as sensors and memories are already being produced. Every hard disk drive has a magnetic sensor that uses a flow of spins, and magnetic random access memory (MRAM) chips are becoming increasingly popular.

Over the last decade, exciting results have been made in the field of graphene spintronics, evolving to a next generation of studies extending to new two-dimensional (2D) compounds.

Since its isolation in 2004, graphene has opened the door for other 2D materials. Researchers can then use these materials to create stacks of 2D materials called heterostructures. These can be combined with graphene to create new ‘designer materials’ to produce applications originally limited to science fiction.

Professor Francisco Guinea who co-authored the paper said: “The field of spintronics, the properties and manipulation of spins in materials has brought to light a number of novel aspects in the behaviour of solids. The study of fundamental aspects of the motion of spin carrying electrons is one of the most active fields in the physics of condensed matter.”

The identification and characterisation of new quantum materials with non-trivial topological electronic and magnetic properties is being intensively studied worldwide, after the formulation, in 2004 of the concept of topological insulators. Spintronics lies at the core of this search. Because of their purity, strength, and simplicity, two dimensional materials are the best platform where to find these unique topological features which relate quantum physics, electronics, and magnetism.”

Overall, the field of spintronics in graphene and related 2D materials is currently moving towards the demonstration of practical graphene spintronic devices such as coupled nano-oscillators for applications in fields of space communication, high?speed radio links, vehicle radar and interchip communication applications.

Advanced materials is one of The University of Manchester’s research beacons — examples of pioneering discoveries, interdisciplinary collaboration and cross-sector partnerships that are tackling some of the biggest questions facing the planet. #ResearchBeacons

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Scientists pioneer new way to study exoplanets

A team of scientists using the Low Frequency Array (LOFAR) radio telescope in the Netherlands has observed radio waves that carry the distinct signatures of aurorae, caused by the interaction between a star’s magnetic field and a planet in orbit around it.

Radio emission from a star-planet interaction has been long predicted, but this is the first time astronomers have been able to detect and decipher these signals. The discovery paves the way for a novel and unique way to probe the environment around exoplanets — planets that orbit stars in other solar systems — and to determine their habitability.

Notably, follow-up observations with the HARPS-N telescope in Spain ruled out the alternate possibility that the interacting companion is another star as opposed to an exoplanet.

The work appears in articles in Nature Astronomy and Astrophysical Journal Letters (ApJL).

The breakthrough centered on red dwarfs, which are the most abundant type of star in our Milky Way — but much smaller and cooler than our own Sun. This means for a planet to be habitable, it has to be significantly closer to its star than the Earth is to the Sun.

Red dwarfs also have much stronger magnetic fields than the Sun, which means that a habitable planet around a red dwarf is exposed to intense magnetic activity. This can heat the planet and even erode its atmosphere. The radio emissions associated with this process are one of the only tools available to probe the interaction between such planets and their stars.

“The motion of the planet through a red dwarf’s strong magnetic field acts like an electric engine much in the same way a bicycle dynamo works,” says Harish Vedantham, the lead author of the Nature Astronomy study and a Netherlands Institute for Radio Astronomy (ASTRON) staff scientist. “This generates a huge current that powers aurorae and radio emission on the star.”

Thanks to the Sun’s weak magnetic field and the larger distance to the planets, similar currents are not generated in the solar system. However, the interaction of Jupiter’s moon Io with Jupiter’s magnetic field generates a similarly bright radio emission, even outshining the Sun at sufficiently low frequencies.

“We adapted the knowledge from decades of radio observations of Jupiter to the case of this star,” says Joe Callingham, ASTRON postdoctoral fellow and co-author of the Nature Astronomy paper. “A scaled-up version of Jupiter-Io has long been predicted to exist in star-planet systems, and the emission we observed fits the theory very well.”

To be sure, the astronomers had to rule out an alternate possibility — that the interacting bodies are two stars in a close binary system instead of a star and its exoplanet. The team searched for the signature of a companion star using the HARPS-N instrument (High Accuracy Radial Velocity Planet Searcher) on the Italian Telescopio Nazionale Galileo on La Palma, Spain.

“Interacting binary stars can also emit radio waves,” notes Benjamin Pope, NASA Sagan Fellow at New York University and lead author of the ApJL paper. “Using optical observations to follow up, we searched for evidence of a stellar companion masquerading as an exoplanet in the radio data. We ruled this scenario out very strongly, so we think the most likely possibility is an Earth-sized planet too small to detect with our optical instruments.”

The group is now concentrating on finding similar emission from other stars.

“We now know that nearly every red dwarf hosts terrestrial planets, so there must be other stars showing similar emission,” observes Callingham, also a co-author of the ApJL paper. “We want to know how this impacts our search for another Earth around another star.”

“If we find that most red dwarf planets are blasted by intense stellar winds, this is bad news for their habitability,” Pope, part of NYU’s Department of Physics and Center for Data Science and a co-author of the Nature Astronomy paper.

The group expects this new method of detecting exoplanets will open up a new way of understanding the habitat of exoplanets.

“The long-term aim is to determine what impact the star’s magnetic activity has on an exoplanet’s habitability, and radio emissions are a big piece of that puzzle,” says Vedantham, also a co-author of the ApJL paper. “Our work has shown that this is viable with the new generation of radio telescopes and put us on an exciting path.”

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3D Printing Industry

Prize winning space-time research expands design for additive manufacturing

Researchers from the Delft University of Technology (TU Delft) in the Netherlands have developed a method to concurrently optimize 3D printed structures and the fabrication sequence that creates them, specifically in the wire arc additive manufacturing process (WAAM).  The method comprises a topology optimization formulation capable of simultaneously enhancing the density field for defining the […]

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Author: Anas Essop

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DiManEx adopts Logistyx software for additive manufacturing supply chain platform

DiManEx, a 3D printing supply chain software provider based in the Netherlands, has partnered with Logistyx Technologies, a U.S. developer of transportation management solutions for parcel shipping. Through the collaboration, DiManEx has selected Logistyx’s TME solution to manage its multi-carrier parcel deliveries. “We see smaller, more frequent deliveries happening everywhere, and shipping parcels demands a […]

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Author: Anas Essop

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Soil on moon and Mars likely to support crops

Researchers at Wageningen University & Research in the Netherlands have produced crops in Mars and Moon soil simulant developed by NASA. The research supports the idea that it would not only be possible to grow food on Mars and the Moon to feed future settlers, but also to obtain viable seed from crops grown there.

Wieger Wamelink and his colleagues at Wageningen University & Research, cultivated ten different crops: garden cress, rocket, tomato, radish, rye, quinoa, spinach, chives, peas and leek. The researchers simulated the properties of Lunar and Martian regolith and “normal” soil (potting soil from Earth) as a control.

Nine of the ten crops sown grew well and edible parts were harvested from them. Spinach was the exception. Total biomass production per tray was the highest for the Earth control and Mars soil simulant that differed significantly from Moon soil simulant. The seeds produced by three species (radish, rye and garden cress) were tested successfully for germination.

The article, “Crop growth and viability of seeds on Mars and Moon soil simulants,” by Wieger Wamelink and colleagues has been published in De Gruyter’s open access journal, Open Agriculture.

“We were thrilled when we saw the first tomatoes ever grown on Mars soil simulant turning red. It meant that the next step towards a sustainable closed agricultural ecosystem had been taken,” said Wieger Wamelink.

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Watching energy transport through biomimetic nanotubes

Scientists from the University of Groningen (the Netherlands) and the University of Würzburg (Germany) have investigated a simple biomimetic light-harvesting system using advanced spectroscopy combined with a microfluidic platform. The double-walled nanotubes work very efficiently at low light intensities, while they are able to get rid of excess energy at high intensities. These properties are useful in the design of novel materials for the harvesting and transport of photon energy. The results were published in the journal Nature Communications on 10 October.

The remarkable ability of natural photosynthetic complexes to efficiently harness sunlight — even in dark environments — has sparked widespread interest in deciphering their functionality. Understanding energy transport on the nanoscale is key for a range of potential applications in the field of (opto)electronics. The overwhelming complexity of natural photosynthetic systems, consisting of many hierarchically arranged sub-units, led scientists to turn their attention to biomimetic analogs, which are structured like their natural counterparts but can be more easily controlled.

Ligh-harvesting molecules

The Optical Condensed Matter Science group and the Theory of Condensed Matter group (both at the Zernike Institute for Advanced Materials, University of Groningen) have joined forces with colleagues from the University of Würzburg (Germany) to gain a comprehensive picture of energy transport in an artificial light-harvesting complex. They used a new spectroscopic lab-on-a-chip approach, which combines advanced time-resolved multidimensional spectroscopy, microfluidics, and extensive theoretical modeling.

The scientists investigated an artificial light-harvesting device, inspired by the multi-walled tubular antenna network of photosynthetic bacteria found in nature. The biomimetic device consists of nanotubes made out of light-harvesting molecules, self-assembled into a double-walled nanotube. ‘However, even this system is rather complex,’ explains Maxim Pshenichnikov, professor of ultrafast spectroscopy at the University of Groningen. His group devised a microfluidic system, in which the outer wall of the tube can be selectively dissolved and, thus, switched off. ‘This is not stable, but in the flow system, it can be studied.’ In this way, the scientists could study both the inner tube and the complete system.

Adapting

At low light intensity, the system absorbs photons in both walls, creating excitations or excitons. ‘Due to the different sizes of the walls, they absorb photons of different wavelengths,’ Pshenichnikov explains. ‘This increases the efficiency.’ At high light intensity, a large number of photons are absorbed, creating a huge number of excitons. ‘We observed that, when two excitons meet, one of them actually ceases to exist.’ This effect acts as a kind of safety valve, as high numbers of excitons could damage the nanotubes.

Thus, the scientists also demonstrated that the double-walled molecular nanotube is capable of adapting to changing illumination conditions. They mimic the essential functional elements of nature’s design toolbox at low light conditions by acting as highly sensitive antennas but get rid of excess energy at high intensities when there is too much light — a situation that would not normally occur in nature. Both these properties pave the way for better control of the transport of energy through complex molecular materials.

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Builder 3D Printers help reconstruct 67 million-year-old dinosaur skeleton for Naturalis museum in the Netherlands

The Naturalis Biodiversity Center, a national research institute for biodiversity located in the Netherlands has used 3D printing and 3D scanning to help reconstruct a triceratops skeleton. Using the Builder Extreme 1500 PRO 3D printer from Builder 3D Printers, Naturalis was able to replace the missing bones of a new exhibit using scans of other […]

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Author: Anas Essop

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TU Delft engineers develop self-aware 3D printed soft robots

Researchers from the Delft University of Technology (TU Delft) in the Netherlands, have created mulitcolored 3D printed sensors to aid the self-awareness and adaptability of soft robots. As stated by Rob Scharff, the first author of the study published in IEEE/ASME Transactions on Mechatronics, soft robots can bend, stretch and twist at the same time, making existing sensors […]

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Author: Tia Vialva