Magnetic vortex memory shows memory potential of nanodots

Apr 21, 2010 By Lisa Zyga feature
In this illustration of the frequency-controlled magnetic memory, a magnetic spherical probe attached to the end of a soft cantilever is used to detect magnetization dynamics in the vortex-state nanodisk underneath. Image credit: B. Pigeau, et al.

(PhysOrg.com) -- Using magnetic nanodots in the vortex state, researchers have designed a new kind of non-volatile memory that could offer increased speed and density for next-generation non-volatile random access memories (RAM). The new design takes advantage of magnetic vortices' ability to store binary information as positive or negative core polarities, which can be controlled by simply changing the frequency of the rotating vortex cores of the nanodots.

The new technique, called frequency-controlled magnetic vortex memory, was developed by a team of researchers, B. Pigeau, et al., from France, Germany, and the US. Their study is published in a recent issue of .

As the researchers explain, the concept of using magnetic nano-objects to store binary information for magnetic RAM has previously been investigated, but it’s been difficult to find a mechanism to reverse the magnetization inside individual nano-objects. Here, the researchers achieve this reversal by using microwave pulses in combination with a static magnetic field. In this scheme, large and small rotating core frequencies are associated with positive and negative core polarities, respectively. In a positive core polarity, the core is parallel to the applied magnetic field, while in a negative core polarity, the core is antiparallel to the applied magnetic field. An extremely sensitive magnetic resonance force microscope (MRFM) is used to address the of magnetic nanodots’ vortex core rotations, allowing the researchers to control the polarity states of individual nanodots.

The researchers’ memory design consists of an array of magnetic nanodots and an that generates a static magnetic field perpendicular to the array of dots. The MRFM’s small (800-nanometer-diameter) magnetic probe can scan the one-micrometer-diameter nanodots and locally control this magnetic field.

To read the core polarity state of a nanodot, a weak microwave magnetic field is used to read the rotating core frequency with the probe. As the researchers explain, the microwave magnetic field used to read the polarity state must be weak enough so that the core polarity is not reversed during the reading sequence.

By increasing the strength of this applied microwave , it is possible to reverse the nanodot’s core polarity, hence to write data. Once reversed, the core polarity is out of resonance with the writing pulse so that it cannot be switched back unless the pulse’s frequency is changed. The researchers demonstrated this writing technique hundreds of times without failure, and without affecting neighboring nanodots.

“This dynamical reversal mechanism is of fundamental interest but also has potential application in information technology, with the vortex core polarity coding the binary information,” coauthor Grégoire de Loubens, from the Commissariat à l'Énergie Atomique de Saclay in Gif-sur-Yvette, France, told PhysOrg.com.

“In sum, our frequency-controlled magnetic vortex memory prototype has two main advantages,” he said. “Owing to the frequency discrimination allowed by a small perpendicular bias field, there is no need to control the circular polarization of the microwave field and to precisely time the writing pulse as it has to be in zero field. Also, deterministic and local addressing in a large array of memory cells is easily obtained by using the stray-field of the MRFM probe, that can be scanned laterally.”

The researchers plan to improve the new frequency-controlled magnetic memory in several ways, such as by arranging the dots in a regular square array and increasing the dot aspect ratio. They are also considering replacing the MRFM, which contains moving parts, with local electrical detectors for the reading process. In addition, they hope to investigate stacking dots of different aspect ratios (and different resonance frequencies) on top of each other to create a multiregister memory.

Explore further: Study reveals new characteristics of complex oxide surfaces

More information: B. Pigeau, et al. “A frequency-controlled magnetic vortex memory.” Applied Physics Letters 96, 132506 (2010). Doi:10.1063/1.3373833
Nanomagnetism Group webpage: Frequency control of vortex core polarity in a magnetic nanodisk iramis.cea.fr/spec/Phocea/Vie_… marquant&id_ast=1567

4.9 /5 (15 votes)

Related Stories

Lava flows reveal clues to magnetic field reversals

Sep 25, 2008

(PhysOrg.com) -- Ancient lava flows are guiding a better understanding of what generates and controls the Earth's magnetic field — and what may drive it to occasionally reverse direction.

Magnetic Vortex Switch Leads to Electric Pulse

Apr 08, 2009

(PhysOrg.com) -- Researchers at the University of Arkansas have shown that changing the chirality, or direction of spin, of a nanoscale magnetic vortex creates an electric pulse, suggesting that such a pulse might be of use ...

New Nanoparticle Structure Boosts Magnetic Properties

Dec 19, 2005

Magnetic nanoparticles have shown promise as contrast-enhancing agents for improving cancer detection using magnetic resonance imaging (MRI), as miniaturized heaters capable of killing malignant cells, and as targeted drug ...

Recommended for you

A new way to make microstructured surfaces

19 hours ago

A team of researchers has created a new way of manufacturing microstructured surfaces that have novel three-dimensional textures. These surfaces, made by self-assembly of carbon nanotubes, could exhibit a ...

Tough foam from tiny sheets

Jul 29, 2014

Tough, ultralight foam of atom-thick sheets can be made to any size and shape through a chemical process invented at Rice University.

User comments : 4

Adjust slider to filter visible comments by rank

Display comments: newest first

ddoingit1
Apr 21, 2010
This comment has been removed by a moderator.
MobReign
5 / 5 (1) Apr 21, 2010
@ddoingit1

if only it was that easy

Also, is your website true, false or somewhere else?
Parsec
not rated yet Apr 21, 2010
Incasements by oxygen and magnified inner chamber by reflective nano technological solid state compisits will enhance the spheric redirections into solidified proton beams of computations magnetic the chambers vertex and delivery a nuematic cortex, self sustain intagers reprocess by grid magnetic grounding positive direct battery cells and demonstrtae a desolving molecular re ignitions into a galactic measurements of oscilatory perionics and redefine the substance of periodic tables
http://ddoingit1.posterous.com


Wow... I guess that explains that! Or something. Or maybe just a madhouse compendium of disjointed and misspelled technical words and phrases thrown into a random jumble. I vote for the latter.
PinkElephant
not rated yet Apr 22, 2010
ddoingit1 is a bot. Click "report abuse" on it, so that its account can be blocked by the moderators...
SongDog
not rated yet Apr 27, 2010
Interesting proof-of-concept, grossly impractical as is. The full paper (an earlier version) is here: http://arxiv.org/pdf/1003.0158 and also here: http://en.scienti...55066305