Featured Research

from universities, journals, and other organizations

Magnetic switching simplified

Date:
August 7, 2013
Source:
Helmholtz Association
Summary:
Researchers have described a new physical effect that could be used to develop more efficient magnetic chips for information processing. The quantum mechanical effect makes it easier to produce spin-polarized currents necessary for the switching of magnetically stored information.

Spin current (blue) and spin accumulation (red) in layer systems composed of platinum (bottom) and cobalt produce a torque that influences the orientation of the magnetic moments in the cobalt layer (illustrated by the red and green bar magnets).
Credit: Forschungszentrum Jülich

An international team of researchers has described a new physical effect that could be used to develop more efficient magnetic chips for information processing. The quantum mechanical effect makes it easier to produce spin-polarized currents necessary for the switching of magnetically stored information. The research findings were published online on 28 July in the high-impact journal Nature Nanotechnology.

Random-access memory is the short-term memory in computers. It buffers the programs and files currently in use in electronic form, in numerous tiny capacitors. As capacitors discharge over time, they have to be recharged regularly to ensure that no data are lost. This costs time and energy, and an unplanned power failure can result in data being lost for good.

Magnetic Random Access Memories (MRAMs), on the other hand, store information in tiny magnetic areas. This is a fast process that functions without a continuous power supply. In spite of this, MRAMs have yet to be implemented on a large scale, as their integration density is still too low, and they use too much energy, are difficult to produce, and cost too much.

One reason for this is that spin-polarized currents, or spin currents for short, are needed to switch the magnetic areas of the MRAMs. Spin is the intrinsic angular momentum of electrons that gives materials their magnetic properties, and it can point in two directions. Spin currents are electric currents that possess only one of these two spin types. Similar to the way in which Earth's magnetic field affects the needle of a compass, a current of one of the spin types influences a magnetic layer and can cause it to flip.

To produce spin currents up to now, the desired spin type was filtered from normal electric current. This required special filter structures and high current densities. Thanks to the new effect identified by researchers from Jülich, Barcelona, Grenoble, and Zurich, magnetic information could now be switched more easily.

"We no longer need spin filters. Instead, we produce the spin current directly where it will be used. All that is needed is a layer stack made of cobalt and platinum," says Dr. Frank Freimuth from the Peter Grünberg Institute and the Institute for Advanced Simulation at Forschungszentrum Jülich. This reduces the amount of space required, makes the system more robust, and may simplify the production of magnetic chips.

An electric current, conducted through the stack at the interface, separates the spins in the platinum layer and transports only one spin type into the magnetic cobalt layer. This creates a torque in this layer that can reverse the magnetization. "Spin torques had already been observed in double layer systems in the past," says the physicist, who is part of the Young Investigators Group on Topical Nanoelectronics headed by Prof. Yuriy Mokrousov. "The fact that we have conclusively explained for the first time how they are created is a scientific breakthrough, because this will enable us to produce them selectively and investigate them in more detail."

The researchers identified two mechanisms that combine to produce the new effect, which they have dubbed 'spin-orbit torque': spin-orbit coupling and the exchange interaction. Spin-orbit coupling is a well-known relativistic quantum phenomenon and the reason why all electron spins of one type move from the platinum to the cobalt layer. Within the cobalt layer, the layer's magnetic orientation then interacts with the spins via the exchange interaction.

The researchers tested their theory successfully in experiments. Their next step is to calculate the effect in other materials with stronger spin-torque coupling to find out whether the effect is even more apparent in other material combinations.


Story Source:

The above story is based on materials provided by Helmholtz Association. Note: Materials may be edited for content and length.


Journal Reference:

  1. Kevin Garello, Ioan Mihai Miron, Can Onur Avci, Frank Freimuth, Yuriy Mokrousov, Stefan Blügel, Stéphane Auffret, Olivier Boulle, Gilles Gaudin, Pietro Gambardella. Symmetry and magnitude of spin–orbit torques in ferromagnetic heterostructures. Nature Nanotechnology, 2013; 8 (8): 587 DOI: 10.1038/NNANO.2013.145

Cite This Page:

Helmholtz Association. "Magnetic switching simplified." ScienceDaily. ScienceDaily, 7 August 2013. <www.sciencedaily.com/releases/2013/08/130807134133.htm>.
Helmholtz Association. (2013, August 7). Magnetic switching simplified. ScienceDaily. Retrieved April 23, 2014 from www.sciencedaily.com/releases/2013/08/130807134133.htm
Helmholtz Association. "Magnetic switching simplified." ScienceDaily. www.sciencedaily.com/releases/2013/08/130807134133.htm (accessed April 23, 2014).

Share This



More Matter & Energy News

Wednesday, April 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Air Force: $4.2B Saved from Grounding A-10s

Air Force: $4.2B Saved from Grounding A-10s

AP (Apr. 23, 2014) — Speaking about the future of the United States Air Force, Chief of Staff Gen. Mark Welsh says the choice to divest the A-10 fleet was logical and least impactful. (April 23) Video provided by AP
Powered by NewsLook.com
Is North Korea Planning Nuclear Test #4?

Is North Korea Planning Nuclear Test #4?

Newsy (Apr. 22, 2014) — South Korean officials say North Korea is preparing to conduct another nuclear test, but is Pyongyang just bluffing this time? Video provided by Newsy
Powered by NewsLook.com
China Falls for 4x4s at Beijing Auto Show

China Falls for 4x4s at Beijing Auto Show

AFP (Apr. 22, 2014) — The urban 4x4 is the latest must-have for Chinese drivers, whose conversion to the cult of the SUV is the talking point of this year's Beijing auto show. Duration: 00:40 Video provided by AFP
Powered by NewsLook.com
Hagel Gets Preview of New High-Tech Projects

Hagel Gets Preview of New High-Tech Projects

AP (Apr. 22, 2014) — Defense Secretary Chuck Hagel is given hands-on demonstrations Tuesday of some of the newest research from DARPA _ the military's Defense Advanced Research Projects Agency program. (April 22) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins