Posts belonging to Category spintronics



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.

CLICK ON THE IMAGE TO ENJOY THE VIDEO

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/
AND
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