Walls falling faster for solid-state memory

Jun 09, 2010

After running a series of complex computer simulations, researchers have found that flaws in the structure of magnetic nanoscale wires play an important role in determining the operating speed of novel devices using such nanowires to store and process information. The finding, made by researchers from the National Institute of Standards and Technology, the University of Maryland, and the University of Paris XI, will help to deepen the physical understanding and guide the interpretation of future experiments of these next-generation devices.

Magnetic nanowires store information in discrete bands of magnetic spins. One can imagine the nanowire like a straw sucking up and holding the liquid of a meticulously layered chocolate and vanilla milkshake, with the chocolate segments representing 1s and the vanilla 0s. The boundaries between these layers are called . Researchers manipulate the information stored on the nanowire using an electrical current to push the domain walls, and the information they enclose, through the wire and past immobile read and write heads.

Interpretations of experiments seeking to measure how domain walls move have largely ignored the effects of "disorder"—usually the result of defects or impurities in the structure of the nanowires. To see how disorder affects the motion of these microscopic magnetic domains, NIST researchers and their colleagues introduced disorder into their .

Their simulations showed that disorder, which causes friction within the , can increase the rate at which a current can move domain walls.

According to NIST physicist Mark Stiles, friction can cause the domain walls to move faster because they need to lose energy in order to move down the wire.

For example, when a spins, it resists the force of gravity. If a little friction is introduced into the gyroscope's bearing, the gyroscope will fall over more quickly. Similarly, in the absence of damping, a domain wall will only move from one side of the nanowire to the other. Disorder within the nanowire enables the domain walls to lose energy, which gives them the freedom to "fall" down the length of the wire as they move back and forth.

"We can say that the domain wall is moving as if it were in a system that has considerably greater effective damping than the actual damping," says NIST physicist and lead researcher Hongki Min. "This increase in the effective damping is significant enough that it should affect the interpretation of most future domain wall experiments."

Explore further: Study sheds new light on why batteries go bad

More information: H. Min, R.D. McMichael, M.J. Donahue, J. Miltat and M.D. Stiles. Effects of disorder and internal dynamics on vortex wall propagation. Phys. Rev. Lett. 104, 217201. May 26, 2010. prl.aps.org/abstract/PRL/v104/i21/e217201

Related Stories

Nanoscale Dominoes: Magnetic Moments Topple Over in Rows

Sep 24, 2008

Physicists at the Institut für Festkörperforschung in Germany have discovered a type of domino effect in rows of individual manganese atoms on a nickel surface. They determined that the magnetic arrangement of these nanowires ...

When the neighbor's noise makes its way through the walls

Nov 06, 2008

Manufacturers of partition walls will possibly have to think further ahead in future than they have up to now: Christoph Kling shows in his dissertation at the Physikalisch-Technische Bundesanstalt (Germany) that the repercussion ...

Domain registry on the rise

Apr 27, 2006

Internet domain names may become as ubiquitous as Social Security numbers one day, according to Dotster Inc.

Tiny superconductors withstand stronger magnetic fields

Feb 04, 2005

Ultrathin superconducting wires can withstand stronger magnetic fields than larger wires made from the same material, researchers now report. This finding may be useful for technologies that employ superconducting ...

74,000 .eu domain names suspended

Jul 24, 2006

At least 74,000 domain names ending with .eu have been suspended for abusive behavior by a group that controls the name.

Recommended for you

Study sheds new light on why batteries go bad

Sep 14, 2014

A comprehensive look at how tiny particles in a lithium ion battery electrode behave shows that rapid-charging the battery and using it to do high-power, rapidly draining work may not be as damaging as researchers ...

Moving silicon atoms in graphene with atomic precision

Sep 12, 2014

Richard Feynman famously posed the question in 1959: is it possible to see and manipulate individual atoms in materials? For a time his vision seemed more science fiction than science, but starting with groundbreaking ...

Researchers create world's largest DNA origami

Sep 11, 2014

Researchers from North Carolina State University, Duke University and the University of Copenhagen have created the world's largest DNA origami, which are nanoscale constructions with applications ranging ...

Excitonic dark states shed light on TMDC atomic layers

Sep 11, 2014

(Phys.org) —A team of Berkeley Lab researchers believes it has uncovered the secret behind the unusual optoelectronic properties of single atomic layers of transition metal dichalcogenide (TMDC) materials, ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (1) Jun 09, 2010
NIST should have its own football team consisting of Super Androids of its own design... Go NIST! Go NIST!
not rated yet Jun 16, 2010
Huh? Effects of disorder and internal dynamics on vortex wall propagation? Sometimes I wonder why I am a participant in Physorg...... :-)