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Showing posts with label nanomagnet. Show all posts
Showing posts with label nanomagnet. Show all posts

October 04, 2014

3D nanomagnetic logic could extend computer speed improvement

lectrical engineers at the Technische Universität München (TUM) have demonstrated a new kind of building block for digital integrated circuits. Their experiments show that future computer chips could be based on three-dimensional arrangements of nanometer-scale magnets instead of transistors. As the main enabling technology of the semiconductor industry – CMOS fabrication of silicon chips – approaches fundamental limits, the TUM researchers and collaborators at the University of Notre Dame are exploring "magnetic computing" as an alternative.

In a 3D stack of nanomagnets, the researchers have implemented a so-called majority logic gate, which could serve as a programmable switch in a digital circuit. They explain the underlying principle with a simple illustration: Think of the way ordinary bar magnets behave when you bring them near each other, with opposite poles attracting and like poles repelling each other. Now imagine bringing several bar magnets together and holding all but one in a fixed position. Their magnetic fields can be thought of as being coupled into one, and the "north-south" polarity of the magnet that is free to flip will be determined by the orientation of the majority of fixed magnets.

Gates made from field-coupled nanomagnets work in an analogous way, with the reversal of polarity representing a switch between Boolean logic states, the binary digits 1 and 0. In the 3D majority gate reported by the TUM-Notre Dame team, the state of the device is determined by three input magnets, one of which sits 60 nanometers below the other two, and is read out by a single output magnet.



Journal Nanotechnology - Majority logic gate for 3D magnetic computing

December 15, 2012

MeRAM is up to 1,000 times more energy-efficient than current technologies

UCLA - By using electric voltage instead of a flowing electric current, researchers from UCLA's Henry Samueli School of Engineering and Applied Science have made major improvements to an ultra-fast, high-capacity class of computer memory known as magnetoresistive random access memory, or MRAM.

The UCLA team's improved memory, which they call MeRAM for magnetoelectric random access memory, has great potential to be used in future memory chips for almost all electronic applications, including smart-phones, tablets, computers and microprocessors, as well as for data storage, like the solid-state disks used in computers and large data centers.

MeRAM's key advantage over existing technologies is that it combines extraordinary low energy with very high density, high-speed reading and writing times, and non-volatility — the ability to retain data when no power is applied, similar to hard disk drives and flash memory sticks, but MeRAM is much faster.



August 08, 2012

Nanodisk Magnetic Vortices are asymmetric

The phenomenon in ferromagnetic nanodisks of magnetic vortices – hurricanes of magnetism only a few atoms across – has generated intense interest in the high-tech community because of the potential application of these vortices in non-volatile Random Access Memory (RAM) data storage systems. New findings from scientists at the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) indicate that the road to magnetic vortex RAM might be more difficult to navigate than previously supposed, but there might be unexpected rewards as well.

In an experiment made possible by the unique X-ray beams at Berkeley Lab’s Advanced Light Source (ALS), a team of researchers led by Peter Fischer and Mi-Young Im of the Center for X-Ray Optics (CXRO), in collaboration with scientists in Japan, discovered that contrary to what was previously believed, the formation of magnetic vortices in ferromagnetic nanodisks is an asymmetric phenomenon. It is possible that this breaking of symmetry would lead to failure in a data storage device during its initialization process.

“Our experimental demonstration that the vortex state in a single magnetic nanodisk experiences symmetry breaking during formation means that for data storage purposes, there would probably need to be a lengthy verification process to correct for errors,” Im says. “On the plus side, non-symmetric behavior creates a biasing effect that could be applied to a sensor or a logic device.”


MTXM images of in-plane (a) and out-of-plane (b) magnetic components in an array of permalloy nanodisks. In-plane magnetic rotation is shown by white arrow (a). Core polarization is marked by black (up) and white (down) spots. Image (c) shows the complete vortex configuration of each nanodisk in the array. (Images courtesy of Im and Fischer)

Journal Nature Communications - Symmetry breaking in the formation of magnetic vortex states in a permalloy nanodisk.

June 14, 2012

Switchable nano magnets

Research group at Kiel University switches magnetism of individual molecules

Using individual molecules instead of electronic or magnetic memory cells would revolutionise data storage technology, as molecular memories could be thousand-fold smaller. Scientists of Kiel University took a big step towards developing such molecular data storage. They succeeded in selectively switching on and off the magnetism of individual molecules, so-called spin-crossover complexes, by electrons. The interdisciplinary study is part of the Collaborative Research Centre 677 “Functions by Switching”, which is funded by the German Research Foundation (DFG). The results prove that it is technically possible to store information using molecules.



Angewandte Chemie International Edition - Electron-Induced Spin Crossover of Single Molecules in a Bilayer on Gold

April 29, 2012

Atom-by-atom engineering and magnetometry of tailored nanomagnets

Nature Physics - Atom-by-atom engineering and magnetometry of tailored nanomagnets

Nanomagnets, namely arrays of a few exchange-coupled atomic magnetic moments, possess a rich variety of magnetic properties and are explored as constituents of nanospintronics technologies. They have been realized as magnetic clusters or molecular nanomagnets. Individual nanomagnets, built from magnetic atoms adsorbed onto a nonmagnetic surface (adatoms) coupled by Ruderman–Kittel–Kasuya–Yosida exchange, exhibit a high level of versatility resulting from distance-dependent interactions. Here, we combine spin-resolved scanning tunnelling microscopy, atom manipulation and simulations to tailor nanomagnets ranging from linear chains to complex two-dimensional arrays and perform magnetometry in an atom-by-atom fashion. Distinct ground states of each chain, depending on even or odd numbers of constituent atoms, and magnetic frustration within the arrays have been observed directly. Our work demonstrates real-space access to the magnetic states of tailored nanostructures providing an approach to tackling open fundamental questions in magnetism.


Antiferromagnetic ‘flower’.


September 27, 2011

Block Copolymers used to organize nanostructured magnetic materials

Scientists at the University of Massachusetts Amherst report that for the first time they have designed a much simpler method of preparing ordered magnetic materials than ever before, by coupling magnetic properties to nanostructure formation at low temperatures.

The innovative process allows them to create room-temperature ferromagnetic materials that are stable for long periods more effectively and with fewer steps than more complicated existing methods.

Tew explains that his group’s signature improvement is a one-step method to generate ordered magnetic materials based on cobalt nanostructures by encoding a block copolymer with the appropriate chemical information to self-organize into nanoscopic domains. Block copolymers are made up of two or more single-polymer subunits linked by covalent chemical bonds.


Nature Communications - Room temperature magnetic materials from nanostructured diblock copolymers

September 06, 2011

Innovative nanoparticle purification system uses magnetic fields

Penn State - Innovative nanoparticle purification system uses magnetic fields

A team of Penn State scientists has invented a new system that uses magnetism to purify hybrid nanoparticles -- structures that are composed of two or more kinds of materials in an extremely small particle that is visible only with an electron microscope. Team leaders Mary Beth Williams, an associate professor of chemistry, and Raymond Schaak, a professor of chemistry, explained that the never-before-tried method will help scientists to remove impurities from such particles. The method also will help researchers to distinguish between hybrid nanoparticles that appear to be identical when viewed under an electron microscope, but that have different magnetism -- a great challenge in recent nanoparticle research. The system holds the promise of helping to improve drug-delivery systems, drug-targeting technologies, medical-imaging technologies and electronic information-storage devices. The paper will be published in the journal Agewandte Chemie and is available on the journal's early-online website.


"Nano-olives" are made up of an iron oxide "olive" with an iron and platinum "pimento." Together the components make a highly magnetic particle structure, which may one day be useful for data storage in computers. Penn State Department of Public Information

July 05, 2011

Graphene Spintronic Devices with Molecular Nanomagnets

Nanoletters - Graphene Spintronic Devices with Molecular Nanomagnets

The possibility to graft nano-objects directly on its surface makes graphene particularly appealing for device and sensing applications. Here we report the design and the realization of a novel device made by a graphene nanoconstriction decorated with TbPc2 magnetic molecules (Pc = phthalocyananine), to electrically detect the magnetization reversal of the molecules in proximity with graphene. A magnetoconductivity signal as high as 20% is found for the spin reversal, revealing the uniaxial magnetic anisotropy of the TbPc2 quantum magnets. These results depict the behavior of multiple-field-effect nanotransistors with sensitivity at the single-molecule level.

July 01, 2011

Magnetic memory and logic could achieve ultimate energy efficiency

In magnetic contrast images (top) taken by the Advanced Light Source at Lawrence Berkeley National Laboratory, the bright spots are nanomagnets with their north ends pointing down (represented by red bar below) and the dark spots are north-up nanomagnets (blue). The six nanomagnets form a majority logic gate transistor, where the output on the right of the center bar is determined by the majority of three inputs on the top, left and bottom. Horizontal neighboring magnets tend to point in alternate directions, while vertical neighbors prefer to point in the same direction.

Today’s silicon-based microprocessor chips rely on electric currents, or moving electrons, that generate a lot of waste heat. But microprocessors employing nanometer-sized bar magnets – like tiny refrigerator magnets – for memory, logic and switching operations theoretically would require no moving electrons.

Such chips would dissipate only 18 millielectron volts of energy per operation at room temperature, the minimum allowed by the second law of thermodynamics and called the Landauer limit. That’s 1 million times less energy per operation than consumed by today’s computers.

April 19, 2011

New biosensor microchip could speed up drug development, Stanford researchers say

A microchip with an array of 64 nanosensors. The nanosensors appear as small dark dots in an 8 x 8 grid in the center of the illuminated part of the backlit microchip.

A new biosensor microchip that could hold more than 100,000 magnetically sensitive nanosensors could speed up drug development markedly, Stanford researchers say. The nanosensors analyze how proteins bond – a critical step in drug development. The ultrasensitive sensors can simultaneously monitor thousands of times more proteins than existing technology, deliver results faster and assess the strength of the bonds.

Nature Nanotechnology - Quantification of protein interactions and solution transport using high-density GMR sensor arrays

March 30, 2011

‘Spincasting’ Holds Promise For Creation Of Nanoparticle Thin Films

This is an orientation map of a spin-cast array of FePt nanoparticles. Most nanoparticles are enclosed by a hexagon of six neighboring nanoparticles. Each nanoparticle was color coded according to the angle (in degrees) of the hexagon's orientation.

Researchers from North Carolina State University have investigated the viability of a technique called “spincasting” for creating thin films of nanoparticles on an underlying substrate – an important step in the creation of materials with a variety of uses, from optics to electronics.

Spincasting, which utilizes centrifugal force to distribute a liquid onto a solid substrate, already has a variety of uses. For example, it is used in the electronics industry to deposit organic thin films on silicon wafers to create transistors.

March 28, 2011

Heavy metals open path to high temperature nanomagnets

How would you like to store all the films ever made on a device the size of an Apple iPhone? Magnets made of just a few metallic atoms could make it possible to build radically smaller storage devices and have also recently been proposed as components for spintronics devices. There's just one obstacle on the way. Nano-sized magnets have only been seen to work at temperatures a few hairs above absolute zero.

A chemistry student at the University of Copenhagen has demonstrated that molecular magnets using the metals ruthenium and osmium retain their magnetic properties at higher temperatures. Most likely due to the larger spin-orbit coupling and more diffuse electron cloud present in these heavier elements. Some of his findings have recently been published in Chemistry - A European Journal.

Enhancing the Blocking Temperature in Single-Molecule Magnets by Incorporating 3d–5d Exchange Interactions

January 14, 2011

Hybrid spintronics and straintronics

Applies Physics Letters - Hybrid spintronics and straintronics: A magnetic technology for ultra low energy computing and signal processing

The authors show that the magnetization of a magnetostrictive/piezoelectricmultiferroic single-domain shape-anisotropic nanomagnet can be switched with very small voltages that generate strain in the magnetostrictive layer. This can be the basis of ultralow power computing and signal processing. With appropriate material choice, the energy dissipated per switching event can be reduced to ∼45 kT at room temperature for a switching delay of ∼100 ns and ∼70 kT for a switching delay of ∼10 ns, if the energy barrier separating the two stable magnetization directions is ∼32 kT . Such devices can be powered by harvesting energy exclusively from the environment without the need for a battery.

January 04, 2011

Nanomagnet logic research summary and DARPA funding to achieve energy efficient computing breakthrough

DARPA awarded a $9.9 million contract to Notre Dame’s Center for Nano Science and Technology for advanced nanomagnet logic (NML) research — a promising new field where the transmission and computation of data are accomplished using magnetic fields, rather than electrical current.

The ultimate goal?

Invent a new type of logic/computational platform powered by magnets that will eventually lead to the development and commercialization of an all-magnetic information processing system. Notre Dame researchers have projected that NML processes consume up to 100 times less power than current computer technologies.

Another advantage of magnetic memory is that it is “nonvolatile” — in other words, it doesn’t lose the information it is using when it shuts down. Any computation with NML devices will start up instantly. The DARPA program is scheduled to run 4.5 years. At the end of that time, there should be enough experimental data to show if commercialization of this technology is feasible.

Quick Summary of Relevant Nanomagnet Logic Research

There is a lot of research to determine the right configurations, architecture and operating modes to capture the desired energy efficiency while maximizing speed.

1. This is either the same DARPA funding or related to DARPA funding of Grandis and Notre Dame's work on spin transfer torque random access memory.