Team controls thermal fluctuations with spin current

November 17, 2011

(PhysOrg.com) -- A team of researchers from the NIST Center for Nanoscale Science and Technology, the University of Muenster, and West Virginia University have demonstrated control of magnetic thermal fluctuations using current.

The work, reported in the September 2 issue of , represents an important step towards manipulating the noise properties of magnetic and .

The magnetic fluctuations of a 2 µm-diameter disk of a Ni-Fe alloy (permalloy) were measured using microfocus Brillouin light scattering while a current passed through a supporting Pt strip. The current generated a , which was injected into the permalloy disk through its back surface. As electrons flow along the Pt strip, they scatter differently, depending on each electron’s spin: those with “up” spin scatter slightly toward the top surface, while those with “down” spin scatter slightly toward the bottom surface. This “spin Hall effect” drives a spin current, but not a charge current, into the bottom of the magnetic disk.

The measurements show that the of the disk’s magnetization are suppressed if the injected spins are parallel to the magnet’s spins, and that the fluctuations are strongly amplified if the injected spins and the magnet’s spins are antiparallel. By changing the current down the Pt strip, the fluctuations were controllably reduced to 0.5 times or amplified to 25 times their thermal level. The measured population of the disk’s magnetic excitations differs from a thermal distribution, showing that the effect is not simply cooling or heating.

These intriguing results provide insight into the complexity of spin current phenomena and suggest a route for controllably manipulating fluctuations in future magnetic nanodevices.

Explore further: Creating a pure spin current in graphene

More information: Control of magnetic fluctuations by spin current, V. E. Demidov, S. Urazhdin, E. R. J. Edwards, M. D. Stiles, R. D. McMichael, and S. O. Demokritov, Physical Review Letters 107, 107204 (2011).

Related Stories

Creating a pure spin current in graphene

February 7, 2011

(PhysOrg.com) -- Graphene is a material that has the potential for a number of future applications. Scientists are interested in using graphene for quantum computing and also as a replacement for electronics. However, in ...

New spin on graphene

April 14, 2011

(PhysOrg.com) -- University of Manchester scientists have found a way to make wonder material graphene magnetic, opening up a new range of opportunities for the world’s thinnest material in the area of spintronics.

Unfazed by imperfections

July 8, 2011

While insulating against electrical currents in their interior, the surface of materials called topological insulators permits the flow of electron spins relatively unhindered. The almost lossless flow of spin information ...

Generation of spin current by acoustic wave spin pumping

September 26, 2011

Tohoku University, Japan Science and Technology Agency (JST) and Japan Atomic Energy Agency (JAEA) announced on August 22, 2011 that Kenichi Uchida, a PhD student, and Professor Eiji Saitoh of Tohoku University and their ...

Recommended for you

Graphene under pressure

August 25, 2016

Small balloons made from one-atom-thick material graphene can withstand enormous pressures, much higher than those at the bottom of the deepest ocean, scientists at the University of Manchester report.

Designing ultrasound tools with Lego-like proteins

August 25, 2016

Ultrasound imaging is used around the world to help visualize developing babies and diagnose disease. Sound waves bounce off the tissues, revealing their different densities and shapes. The next step in ultrasound technology ...

Nanovesicles in predictable shapes

August 25, 2016

Beads, disks, bowls and rods: scientists at Radboud University have demonstrated the first methodological approach to control the shapes of nanovesicles. This opens doors for the use of nanovesicles in biomedical applications, ...

'Artificial atom' created in graphene

August 22, 2016

In a tiny quantum prison, electrons behave quite differently as compared to their counterparts in free space. They can only occupy discrete energy levels, much like the electrons in an atom - for this reason, such electron ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.