Posts belonging to Category spintronics



Nanotechnology Boosts CyberSecurity Against Hackers

The next generation of electronic hardware security may be at hand as researchers at New York University Tandon School of Engineering  (NYU Tandon) introduce a new class of unclonable cybersecurity security primitives made of a low-cost nanomaterial with the highest possible level of structural randomness. Randomness is highly desirable for constructing the security primitives that encrypt and thereby secure computer hardware and data physically, rather than by programming.

In a paper published in the journal ACS Nano, Assistant Professor of Electrical and Computer Engineering Davood Shahrjerdi and his team at NYU Tandon offer the first proof of complete spatial randomness in atomically thin molybdenum disulfide (MoS2). The researchers grew the nanomaterial in layers, each roughly one million times thinner than a human hair. By varying the thickness of each layer, Shahrjerdi explained, they tuned the size and type of energy band structure, which in turn affects the properties of the material.

(a) At monolayer thickness, this material has the optical properties of a semiconductor that emits light. At multilayer, the properties change and the material doesn’t emit light. (b) Varying the thickness of each layer results in a thin film speckled with randomly occurring regions that alternately emit or block light. (c) Upon exposure to light, this pattern can be translated into a one-of-a-kind authentication key that could secure hardware components at minimal cost.

This property is unique to this material,” underscores Shahrjerdi. By tuning the material growth process, the resulting thin film is speckled with randomly occurring regions that alternately emit or do not emit light. When exposed to light, this pattern translates into a one-of-a-kind authentication key that could secure hardware components at minimal cost.

Source: http://engineering.nyu.edu/

Graphene Ripples, Clean And Limitless Energy Source

Graphene is a seemingly impossible material. For years, scientists had theorized that lifting a single layer of carbon atoms from a chunk of graphite could produce the first two-dimensional material, which they called graphene. Finally, in 2004, this was accomplished by two physicists at the University of Manchester, who earned the Nobel Prize in Physics for this breakthrough. There was a problem, however: two dimensional materials violate the laws of physics. Without the support of a substrate, physics predicts they would tear apart or melt, even at a temperature of absolute zero. Physicists had to find a loophole to explain their existence.

That loophole turned out to be related to a phenomenon known as Brownian motion, small random fluctuations of the carbon atoms that make up graphene. This causes the material to ripple into the third dimension, similar to waves moving across the surface of the ocean. These movements in and out of the flat surface allow graphene to stay comfortably within the laws of physics.

Ever since Robert Brown discovered Brownian motion in 1827, scientists have wondered whether they could harvest this motion as a source of energy. The research of Paul Thibado, professor of physics at the University of Arkansas, provides strong evidence that the motion of graphene could indeed be used as a source of clean, limitless energy. Other researchers have theorized that temperature-induced curvature inversion in graphene could be used as an energy source, and even predicted the amount of energy they could produce. What sets Thibado’s work apart is his discovery that graphene has naturally occurring ripples that invert their curvature as the atoms vibrate in response to the ambient temperature.

This is the key to using the motion of 2D materials as a source of harvestable energy,” Thibado said. Unlike atoms in a liquid, which move in a random directions, atoms connected in a sheet of graphene move together. This means their energy can be collected using existing nanotechnology.

These results have been published in the journal Physical Review Letters.

Source: https://researchfrontiers.uark.edu

How To Use Computers Heat To Generate Electricity

Electronic devices such as computers generate heat that mostly goes to waste. Physicists at Bielefeld University (Germany) have found a way to use this energy: They apply the heat to generate magnetic signals known as ‘spin currents’. In future, these signals could replace some of the electrical current in electronic components. In a new study, the physicists tested which materials can generate this spin current most effectively from heat. The research was carried out in cooperation with colleagues from the University of Greifswald, Gießen University, and the Leibniz Institute for Solid State and Materials Research in Dresden.

The Bielefeld physicists are working on the basic principles for making data processing more effective and energy-efficient in the young field of ‘spin caloritronics’. They are members of the ‘Thin Films & Physics of Nanostructures’ research group headed by Professor Dr. Günter Reiss. Their new study determines the strength of the spin current for various combinations of thin films.

A spin current is produced by differences in temperature between two ends of an electronic component. These components are extremely small and only one millionth of a millimetre thick. Because they are composed of magnetic materials such as iron, cobalt, or nickel, they are called magnetic nanostructures.

The physicists take two such nanofilms and place a layer of metal oxide between them that is only a few atoms thick. They heat up one of the external films – for example, with a hot nanowire or a focused laser. Electrons with a specific spin orientation then pass through the metal oxide. This produces the spin current. A spin can be conceived as electrons spinning on their own axes – either clockwise or anti-clockwise.

Their findings have been  published  in the research journal ‘Nature Communications’.

Source: https://ekvv.uni-bielefeld.de/

Ultra-fast Data Processing At Nanoscale

Advancement in nanoelectronics, which is the use of nanotechnology in electronic components, has been fueled by the ever-increasing need to shrink the size of electronic devices like nanocomputers in a bid to produce smaller, faster and smarter gadgets such as computers, memory storage devices, displays and medical diagnostic tools.

While most advanced electronic devices are powered by photonics – which involves the use of photons to transmit informationphotonic elements are usually large in size and this greatly limits their use in many advanced nanoelectronics systems. Plasmons, which are waves of electrons that move along the surface of a metal after it is struck by photons, holds great promise for disruptive technologies in nanoelectronics. They are comparable to photons in terms of speed (they also travel with the speed of light), and they are much smaller. This unique property of plasmons makes them ideal for integration with nanoelectronics. However, earlier attempts to harness plasmons as information carriers had little success.

Addressing this technological gap, a research team from the National University of Singapore (NUS) has recently invented a novel “converter” that can harness the speed and small size of plasmons for high frequency data processing and transmission in nanoelectronics.

This innovative transducer can directly convert electrical signals into plasmonic signals, and vice versa, in a single step. By bridging plasmonics and nanoscale electronics, we can potentially make chips run faster and reduce power losses. Our plasmonic-electronic transducer is about 10,000 times smaller than optical elements. We believe it can be readily integrated into existing technologies and can potentially be used in a wide range of applications in the future,” explained Associate Professor Christian Nijhuis from the Department of Chemistry at the NUS Faculty of Science, who is the leader of the research team behind this breakthrough.

This novel discovery was first reported in the journal Nature Photonics.

Source: http://news.nus.edu.sg/

Optical Computer

Researchers at the University of Sydney (Australia) have dramatically slowed digital information carried as light waves by transferring the data into sound waves in an integrated circuit, or microchipTransferring information from the optical to acoustic domain and back again inside a chip is critical for the development of photonic integrated circuits: microchips that use light instead of electrons to manage data.

These chips are being developed for use in telecommunications, optical fibre networks and cloud computing data centers where traditional electronic devices are susceptible to electromagnetic interference, produce too much heat or use too much energy.

The information in our chip in acoustic form travels at a velocity five orders of magnitude slower than in the optical domain,” said Dr Birgit Stiller, research fellow at the University of Sydney and supervisor of the project.

It is like the difference between thunder and lightning,” she said.

This delay allows for the data to be briefly stored and managed inside the chip for processing, retrieval and further transmission as light wavesLight is an excellent carrier of information and is useful for taking data over long distances between continents through fibre-optic cables.

But this speed advantage can become a nuisance when information is being processed in computers and telecommunication systems.

Source: https://sydney.universty.au/

Very Fast Magnetic Data Storage

For almost seventy years now, magnetic tapes and hard disks have been used for data storage in computers. In spite of many new technologies that have been developed in the meantime, the controlled magnetization of a data storage medium remains the first choice for archiving information because of its longevity and low price. As a means of realizing random access memories (RAMs), however, which are used as the main memory for processing data in computers, magnetic storage technologies were long considered inadequate. That is mainly due to its low writing speed and relatively high energy consumption.

In 1956, IBM introduced the first magnetic hard disc, the RAMAC. ETH researchers have now tested a novel magnetic writing technology that could soon be used in the main memories of modern computers

Pietro Gambardella, Professor at the Department of Materials of the Eidgenössische Technische Hochschule Zürich (ETHZ, Switzerland), and his colleagues, together with colleagues at the Physics Department and at the Paul Scherrer Institute (PSI), have now shown that using a novel technique, magnetic storage can still be achieved very fast and without wasting energy.

In 2011, Gambardella and his colleagues already demonstrated a technique that could do just that: An electric current passing through a specially coated semiconductor film inverted the magnetization in a tiny metal dot. This is made possible by a physical effect called spin-orbit-torque. In this effect, a current flowing in a conductor leads to an accumulation of electrons with opposite magnetic moment (spins) at the edges of the conductor. The electron spins, in turn, create a magnetic field that causes the atoms in a nearby magnetic material to change the orientation of their magnetic moments. In a new study the scientists have now investigated how this process works in detail and how fast it is.

The results were recently published in the scientific journal Nature Nanotechnology.

Source: https://www.ethz.ch/

Big Data And Skyrmions

Today’s world, rapidly changing because of “big data”, is encapsulated in trillions of tiny magnetic objects magnetic bits – each of which stores one bit of data in magnetic disk drives.   A group of scientists from the Max Planck Institutes in Halle and Dresden have discovered a new kind of magnetic nano-object in a novel material that could serve as a magnetic bit with cloaking properties to make a magnetic disk drive with no moving parts – a Racetrack Memory – a reality in the near future.

Most digital data is stored in the cloud as magnetic bits within massive numbers of magnetic disk drives.  Over the past several decades these magnetic bits have shrunk by many orders of magnitude, reaching limits where the boundaries of these magnetic regions can have special properties.  In some special materials these boundaries – “magnetic domain walls” – can be described as being topological. What this means is that these walls can be thought of as having a special magical cloak – what is referred to by scientists as “topological protection”.   An important consequence is that such magnetic walls are more stable to perturbations than similar magnetic bits without topological protection that are formed in conventional magnetic materials.  Thus, these “topological magnetic objects could be especially useful for storing1”s and “0”s, the basic elements of digital data.   One such object is a “magnetic skyrmion” which is a tiny magnetic region, perhaps tens to hundreds of atoms wide, separated from a surrounding magnetic region by a chiral domain wall.  Until recently only one type of skyrmion has been found in which it is surrounded by a chiral domain wall that takes the same form in all directions.   But there have been predictions of several other types of skyrmions that were not yet observed.

Now in a paper published in Nature, scientists from Prof. Stuart Parkin’s NISE department at the Max Planck Institute for Microstructure Physics in Halle, Germany, have found a second class of skyrmions, what are called “anti-skyrmions”, in materials synthesized in Prof. Claudia Felser.   The scientists from Halle and Dresden have found these tiny magnetic objects in a special class of versatile magnetic compounds called Heusler compounds.   Of these Heusler compounds, a tiny subset have just the right crystal symmetry to allow for the possibility of forming anti-skyrmions but not skyrmions.

The special cloaking properties of skyrmions makes them of great interest for a radically new form of solid-state memorythe Racetrack Memory. In Racetrack Memory digital data is encoded within magnetic domain walls that are packed closely within nanoscopic magnetic wires.  One of the unique features of Racetrack Memory, which is distinct from all other memories, is that the walls are moved around the nanowires themselves using recent discoveries in spin-orbitronics domain walls.  Very short pulses of current move all the backwards and forwards along the nano-wires. The walls – the magnetic bits – can be read and written by devices incorporated directly into the nanowires themselves, thereby eliminating any mechanical parts.

Source: https://www.cpfs.mpg.de/

How To Store Data At The Molecular Level

From smartphones to nanocomputers or supercomputers, the growing need for smaller and more energy efficient devices has made higher density data storage one of the most important technological quests. Now scientists at the University of Manchester have proved that storing data with a class of molecules known as single-molecule magnets is more feasible than previously thought. The research, led by Dr David Mills and Dr Nicholas Chilton, from the School of Chemistry, is being published in Nature. It shows that magnetic hysteresis, a memory effect that is a prerequisite of any data storage, is possible in individual molecules at -213 °C. This is tantalisingly close to the temperature of liquid nitrogen (-196 °C).

The result means that data storage with single molecules could become a reality because the data servers could be cooled using relatively cheap liquid nitrogen at -196°C instead of far more expensive liquid helium (-269 °C). The research provides proof-of-concept that such technologies could be achievable in the near future.

The potential for molecular data storage is huge. To put it into a consumer context, molecular technologies could store more than 200 terabits of data per square inch – that’s 25,000 GB of information stored in something approximately the size of a 50p coin, compared to Apple’s latest iPhone 7 with a maximum storage of 256 GB.

Single-molecule magnets display a magnetic memory effect that is a requirement of any data storage and molecules containing lanthanide atoms have exhibited this phenomenon at the highest temperatures to date. Lanthanides are rare earth metals used in all forms of everyday electronic devices such as smartphones, tablets and laptops. The team achieved their results using the lanthanide element dysprosium.

This is very exciting as magnetic hysteresis in single molecules implies the ability for binary data storage. Using single molecules for data storage could theoretically give 100 times higher data density than current technologies. Here we are approaching the temperature of liquid nitrogen, which would mean data storage in single molecules becomes much more viable from an economic point of view,’ explains Dr Chilton.

The practical applications of molecular-level data storage could lead to much smaller hard drives that require less energy, meaning data centres across the globe could become a lot more energy efficient.

Source: http://www.manchester.ac.uk/

No More Batteries For Cellphones

University of Washington (UW) researchers have invented a cellphone that requires no batteries — a major leap forward in moving beyond chargers, cords and dying phones. Instead, the phone harvests the few microwatts of power it requires from either ambient radio signals or light.

The team also made Skype calls using its battery-free phone, demonstrating that the prototype made of commercial, off-the-shelf components can receive and transmit speech and communicate with a base station.

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We’ve built what we believe is the first functioning cellphone that consumes almost zero power,” said co-author Shyam Gollakota, an associate professor in the Paul G. Allen School of Computer Science & Engineering at the UW. “To achieve the really, really low power consumption that you need to run a phone by harvesting energy from the environment, we had to fundamentally rethink how these devices are designed.”

The team of UW computer scientists and electrical engineers eliminated a power-hungry step in most modern cellular transmissionsconverting analog signals that convey sound into digital data that a phone can understand. This process consumes so much energy that it’s been impossible to design a phone that can rely on ambient power sources. Instead, the battery-free cellphone takes advantage of tiny vibrations in a phone’s microphone or speaker that occur when a person is talking into a phone or listening to a call.

An antenna connected to those components converts that motion into changes in standard analog radio signal emitted by a cellular base station. This process essentially encodes speech patterns in reflected radio signals in a way that uses almost no power. To transmit speech, the phone uses vibrations from the device’s microphone to encode speech patterns in the reflected signals. To receive speech, it converts encoded radio signals into sound vibrations that that are picked up by the phone’s speaker. In the prototype device, the user presses a button to switch between these two “transmitting” and “listening” modes.

The new technology is detailed in a paper published July 1 in the Proceedings of the Association for Computing Machinery on Interactive, Mobile, Wearable and Ubiquitous Technologies.

Source: http://www.washington.edu/
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http://www.reuters.com/

Nanoweapons Against North Korea

Unless you’re working in the field, you probably never heard about U.S. nanoweapons. This is intentional. The United States, as well as Russia and China, are spending billions of dollars per year developing nanoweapons, but all development is secret. Even after Pravda.ru’s June 6, 2016 headline, “US nano weapon killed Venezuela’s Hugo Chavez, scientists say,” the U.S. offered no response.

Earlier this year, May 5, 2017, North Korea claimed the CIA plotted to kill Kim Jong Un using a radioactive nano poison, similar to the nanoweapon Venezuelan scientists claim the U.S. used to assassinate former Venezuelan President Hugo Chavez. All major media covered North Korea’s claim. These accusations are substantial, but are they true? Let’s address this question.

Unfortunately, until earlier this year, nanoweapons gleaned little media attention. However, in March 2017 that changed with the publication of the book, Nanoweapons: A Growing Threat to Humanity (2017 Potomac Books), which inspired two articles. On March 9, 2017, American Security Today published “Nanoweapons: A Growing Threat to Humanity – Louis A. Del Monte,” and on March 17, 2017, CNBC published “Mini-nukes and mosquito-like robot weapons being primed for future warfare.” Suddenly, the genie was out of the bottle. The CNBC article became the most popular on their website for two days following its publication and garnered 6.5K shares. Still compared to other classes of military weapons, nanoweapons remain obscure. Factually, most people never even heard the term. If you find this surprising, recall most people never heard of stealth aircraft until their highly publicized use during the first Iraq war in 1990. Today, almost everyone that reads the news knows about stealth aircraft. This may become the case with nanoweapons, but for now, it remains obscure to the public.

Given their relative obscurity, we’ll start by defining nanoweapons. A nanoweapon is any military weapon that exploits the power of nanotechnology. This, of course, begs another question: What is nanotechnology? According to the United States National Nanotechnology Initiative’s website, nano.gov, “Nanotechnology is science, engineering, and technology conducted at the nanoscale, which is about 1 to 100 nanometers.” To put this in simple terms, the diameter of a typical human hair equals 100,000 nanometers. This means nanotechnology is invisible to the naked eye or even under an optical microscope.

Source: http://www.huffingtonpost.com/

All Carbon Spin Transistor Is Quicker And Smaller

A researcher with the Erik Jonsson School of Engineering and Computer Science at UT Dallas has designed a novel computing system made solely from carbon that might one day replace the silicon transistors that power today’s electronic devices.

The concept brings together an assortment of existing nanoscale technologies and combines them in a new way,” said Dr. Joseph S. Friedman, assistant professor of electrical and computer engineering at UT Dallas who conducted much of the research while he was a doctoral student at Northwestern University.

The resulting all-carbon spin logic proposal, published by lead author Friedman and several collaborators in the June 5 edition of the online journal Nature Communications, is a computing system that Friedman believes could be made smaller than silicon transistors, with increased performance.

Today’s electronic devices are powered by transistors, which are tiny silicon structures that rely on negatively charged electrons moving through the silicon, forming an electric current. Transistors behave like switches, turning current on and off.

In addition to carrying a charge, electrons have another property called spin, which relates to their magnetic properties. In recent years, engineers have been investigating ways to exploit the spin characteristics of electrons to create a new class of transistors and devices called “spintronics.”

Friedman’s all-carbon, spintronic switch functions as a logic gate that relies on a basic tenet of electromagnetics: As an electric current moves through a wire, it creates a magnetic field that wraps around the wire. In addition, a magnetic field near a two-dimensional ribbon of carbon — called a graphene nanoribbon — affects the current flowing through the ribbon. In traditional, silicon-based computers, transistors cannot exploit this phenomenon. Instead, they are connected to one another by wires. The output from one transistor is connected by a wire to the input for the next transistor, and so on in a cascading fashion.

Source: http://www.utdallas.edu/

Spintronics

A team of scientists led by Associate Professor Yang Hyunsoo from the National University of Singapore’s (NUS) Faculty of Engineering has invented a novel ultra-thin multilayer film which could harness the properties of tiny magnetic whirls, known as skyrmions, as information carriers for storing and processing data (nanocomputer) on magnetic media. The nano-sized thin film, which was developed in collaboration with researchers from Brookhaven National Laboratory, Stony Brook University, and Louisiana State University, is a critical step towards the design of data storage devices that use less power and work faster than existing memory technologies.

The digital transformation has resulted in ever-increasing demands for better processing and storing of large amounts of data, as well as improvements in hard drive technology. Since their discovery in magnetic materials in 2009, skyrmions, which are tiny swirling magnetic textures only a few nanometres in size, have been extensively studied as possible information carriers in next-generation data storage and logic devices.

Skyrmions have been shown to exist in layered systems, with a heavy metal placed beneath a ferromagnetic material. Due to the interaction between the different materials, an interfacial symmetry breaking interaction, known as the Dzyaloshinskii-Moriya interaction (DMI), is formed, and this helps to stabilise a skyrmion. However, without an out-of-plane magnetic field present, the stability of the skyrmion is compromised. In addition, due to its tiny size, it is difficult to image the nano-sized materials. The NUS team found that a large DMI could be maintained in multilayer films composed of cobalt and palladium, and this is large enough to stabilise skyrmion spin textures.

skyrmionsThis experiment not only demonstrates the usefulness of L-TEM in studying these systems, but also opens up a completely new material in which skyrmions can be created. Without the need for a biasing field, the design and implementation of skyrmion based devices are significantly simplified. The small size of the skyrmions, combined with the incredible stability generated here, could be potentially useful for the design of next-generation spintronic devices that are energy efficient and can outperform current memory technologies,” explains Professor Yang .

The invention was reported in the journal Nature Communications.

Source: http://news.nus.edu.sg