Subscribe free to our newsletters via your
. 24/7 Space News .

Subscribe free to our newsletters via your

Physics of slow microscopic changes in magnetic structures revealed
by Staff Writers
Sendai, Japan (SPX) Dec 17, 2015

Schematic of domain wall creep. When a very weak magnetic field or electric current is applied to the magnetic wire with domain wall, the domain wall behaves as an elastic interface and slowly moves, creeps. Image courtesy Tohoku University. For a larger version of this image please go here.

The research group of Professor Hideo Ohno and Associate Professor Shunsuke Fukami of Tohoku University has studied in detail, a slow change of microscopic magnetic structures in metallic wires induced by external driving forces, commonly called "creep" motion. This has allowed them to clarify the physics of how the driving forces, magnetic fields or electric currents, act on the magnetic structure.

Previous studies had shown that while the actions of magnetic fields and currents are the same for metallic materials, they are fundamentally different for semiconductor materials.

The present study reveals that in cases where the sample satisfies a certain condition, the current acts on the magnetic structure in a different manner from the magnetic field case, irrespective of the intricacies of the material.

The development of a high-performance magnetic memory device (where the magnetic structure is manipulated by current) has been intensively pursued recently, and the present findings are expected to facilitate the fundamental understanding to achieve the practical application.

The research group fabricated a wire device consisting of a ferromagnetic metal CoFeB, and investigated the universality class of a magnetic domain wall "creep". They evaluated the domain wall velocity for various magnitudes of magnetic field or electric current while keeping the device temperature constant, from which they derived the scaling exponent for the universality class.

The results indicate that the scaling exponent does not depend on factors such as temperature and wire width, for both magnetic field and current cases, confirming the universality of the observed feature. Interestingly, unlike the previous study on metallic systems, they found different universality classes between magnetic field and current-driven domain wall creeps in the present metallic sample.

This means that the actions of a magnetic field and current on the domain wall are fundamentally different from each other. The field-driven "creep" was found to belong to a previously known universality class, whereas the current-driven "creep" was found to belong to a different universality class which cannot be explained by the present theories and the scaling exponent was similar to the one observed previously in the magnetic semiconductor.

From detailed investigations of the behavior of the domain wall under the application of a current, they found that the current gives rise to an adiabatic spin-transfer torque acting on the domain wall which has a different symmetry to the torque induced by a magnetic field.

In other words, it was clarified that, for sample in which stack structure is designed so that the adiabatic spin-transfer torque dominantly affects the domain wall, universal creep characteristics appear irrespective of the nature of material, such as metal or semiconductor, the details of microscopic structure.

The obtained findings shed light on a statistical physics of creep motion of elastic interfaces and development of high-performance magnetic memory devices.


Related Links
Tohoku University
Space Technology News - Applications and Research

Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks DiggDigg RedditReddit GoogleGoogle

Previous Report
The artificial materials that came in from the cold
Berkeley CA (SPX) Dec 15, 2015
It has often been said that nature is history's greatest innovator and if that is true then scientists with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) are learning from the best. Berkeley Lab researchers have developed a freeze-casting technique that enables them to design and create strong, tough and lightweight materials comparable to bones, teet ... read more

XPRIZE verifies moon express launch contract, kicking off new space race

Gaia's sensors scan a lunar transit

SwRI scientists explain why moon rocks contain fewer volatiles than Earth's

All-female Russian crew starts Moon mission test

Study finds evidence for more recent clay formation on Mars

New Mars rover findings revealed at American Geophysical Union Conference

Opportunity performs a week of robotic arm at Marathon Valley

Rocks Rich in Silica Present Puzzles for Mars Rover Team

Researchers Recall Work on First Rendezvous in Space

NASA Accepting Applications for Future Explorers

China drives global patent applications to new high

Australia seeks 'ideas boom' with tax breaks, visa boosts

Agreement with Chinese Space Tech Lab Will Advance Exploration Goals

China launches new communication satellite

China's indigenous SatNav performing well after tests

China launches Yaogan-29 remote sensing satellite

British astronaut docks with ISS as country cheers debut trip

NASA spacewalk to fix ISS rail car

Unscheduled spacewalk likely on Monday

First Briton to travel to ISS blasts off into space

Scientists Launch NASA Rocket into "Speed Bumps" Above Norway

NASA orders second Boeing Crew Mission to ISS

O3b signs agreement with Arianespace for a fourth Soyuz launch

Soyuz receives the Galileo payload for its December 17 liftoff

Monster planet is 'dancing with the stars'

Exoplanets Water Mystery Solved

Nearby star hosts closest alien planet in the 'habitable zone'

ALMA reveals planetary construction sites

Physics of slow microscopic changes in magnetic structures revealed

New metamaterial manipulates sound to improve acoustic imaging

Satellite's Last Days Improve Orbital Decay Predictions

Israel's Amos-5 Satellite Failure Caused by Power Supply Malfunction

Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.