Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > New Phenomenon in Nanodisk Magnetic Vortices Berkeley Lab Researchers Take a Mesocale Look at Magnetic Vortex Formations

MTXM images of in-plane (a) and out-of-plane (b) magnetic components in an array of permalloy nanodisks. In-plane magnetic rotation is shown by white arrow (a). Core polarization is marked by black (up) and white (down) spots. Image (c) shows the complete vortex configuration of each nanodisk in the array. (Images courtesy of Im and Fischer)
MTXM images of in-plane (a) and out-of-plane (b) magnetic components in an array of permalloy nanodisks. In-plane magnetic rotation is shown by white arrow (a). Core polarization is marked by black (up) and white (down) spots. Image (c) shows the complete vortex configuration of each nanodisk in the array.

(Images courtesy of Im and Fischer)

Abstract:
The phenomenon in ferromagnetic nanodisks of magnetic vortices - hurricanes of magnetism only a few atoms across - has generated intense interest in the high-tech community because of the potential application of these vortices in non-volatile Random Access Memory (RAM) data storage systems. New findings from scientists at the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) indicate that the road to magnetic vortex RAM might be more difficult to navigate than previously supposed, but there might be unexpected rewards as well.

New Phenomenon in Nanodisk Magnetic Vortices Berkeley Lab Researchers Take a Mesocale Look at Magnetic Vortex Formations

Berkeley, CA | Posted on August 9th, 2012

In an experiment made possible by the unique X-ray beams at Berkeley Lab's Advanced Light Source (ALS), a team of researchers led by Peter Fischer and Mi-Young Im of the Center for X-Ray Optics (CXRO), in collaboration with scientists in Japan, discovered that contrary to what was previously believed, the formation of magnetic vortices in ferromagnetic nanodisks is an asymmetric phenomenon. It is possible that this breaking of symmetry would lead to failure in a data storage device during its initialization process.

"Our experimental demonstration that the vortex state in a single magnetic nanodisk experiences symmetry breaking during formation means that for data storage purposes, there would probably need to be a lengthy verification process to correct for errors," Im says. "On the plus side, non-symmetric behavior creates a biasing effect that could be applied to a sensor or a logic device."

"Our study is also a nice example of mesoscale science, which brings the nanoscience of the last decade to the next level," Fischer says. "Mesoscale phenomena encompass complexity and functionality over various length scales."

Im and Fischer describe this study in a paper published in the journal Nature Communications. The paper is titled "Symmetry breaking in the formation of magnetic vortex states in a permalloy nanodisk." Co-authoring this paper were Keisuke Yamada, Tomonori Sato, Shinya Kasai, Yoshinobu Nakatani and Teruo Ono.

Magnetic vortex states are generated in ferromagnetic nanodisks because the spin of electrons, which gives rise to magnetic moments, must follow the shape of the disk to ensure closure of magnetic flux lines. This results in the curling of the in-plane magnetization flux lines. At the center of these curling flux lines is a needlelike core, an "eye-of-the-hurricane" that points either up or down with respect to the surface plane of the nanodisk.

"The magnetization of the ferromagnetic nanodisk therefore has two components, the up or down polarity of the core and the chirality (rotation) of the in-plane magnetization, which can be either clockwise or counter-clockwise," Im says. "It has been proposed that these four independent orientations can be used to store binary data in novel non-volatile storage devices."

"The assumption has been that magnetic vortex states would exhibit a perfect symmetry required for vortex-based data-storage devices because the energy states of the four orientations were equivalent, meaning four logical values per unit," Fischer says. "However, we show that if you analyze a sufficiently large ensemble of nanodisks, this is not the case. Our results demonstrate how mesoscale behavior can be significantly different from nanoscale behavior."

The key to the discovery of magnetic vortex symmetry-breaking was the research team's ability to simultaneously observe both chirality and polarity in a large array of nanodisks. Previous studies focused on either the chirality or polarity in a single disk. This simultaneous observation was accomplished using the XM-1 x-ray microscope at ALS beamline 6.1.2. XM-1 provides full-field magnetic transmission soft X-ray microscopy with spatial resolution down to 20 nanometers, thanks in part to the high quality X-ray optics provided by CXRO researchers.

"Magnetic transmission soft X-ray microscopy offers high spatial and temporal resolution imaging with element specific magnetic contrast, making it an ideal method for studying nanoscale spin dynamics, such as vortex core dynamics," Im says. "XM-1 provides a large field of view and therefore very short exposure times per disk."

Im, Fischer and their colleagues fashioned nanodisks from permalloy, a nickel and iron alloy whose magnetic properties have been fully characterized. Using electron-beam lithography they patterned large arrays of disks, each with a radius of 500 nanometers and a thickness of 100 nanometers. The arrays were deposited on silicon-nitride membranes to allow for sufficient transmission of soft X-rays and exposed in XM-1 for a few seconds. In their paper, the authors conclude that the observed symmetry breaking most likely results from a combination of intrinsic and extrinsic factors. The intrinsic factor is believed to be an antisymmetric coupling between the spins of two electrons called the Dzyaloshinskii-Moriya interaction. Extrinsic factors include defects along the edges of the nanodisks and rough nanodisk surfaces.

"Our finding is certainly a new physical phenomenon in magnetic vortices, which has not been explored so far," says Im. "The statistical significance of our experimental work and our rigorous 3D micromagnetic simulation for the generation process of vortex state provides important new information for the less known physics in the magnetization process of nanodisks."

"We've also shown that deterministic behavior and functionality on the mesoscale cannot always be extrapolated from even a complete understanding of nanoscale behavior," Fischer says. "In other words, understanding a single LEGO brick might not be enough to build a large and complex structure."

Im is the corresponding author of the Nature Communications paper. Co-authors Yamada and Ono are with Kyoto University, co-authors Sato and Nakatani are with the University of Electro-Communications at Chofu, and co-author Kasai is with Japan's and National Institute for Materials Science.

This research was supported by the DOE Office of Science.

####

About Berkeley Lab
Lawrence Berkeley National Laboratory (Berkeley Lab) addresses the worlds most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Labs scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energys Office of Science. For more, visit www.lbl.gov.

DOEs Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit the Office of Science website at science.energy.gov/.

For more information, please click here

Contacts:
Lynn Yarris
(510) 486-5375

Copyright © Berkeley Lab

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

For more about the research of Peter Fischer and Mi-Young Im go here:

For more about the Center for X-ray Optics go here:

For more about the Advanced Light Source go here:

Related News Press

News and information

Ultrathin device harvests electricity from human motion July 23rd, 2017

The July 23 close fly-by of asteroid 2017 BS5 is explored in a Q&A with Dr. John S. Lewis, chief scientist at Deep Space Industries July 23rd, 2017

Scientists announce the quest for high-index materials: All-dielectric nanophotonics: The quest for better materials and fabrication techniques July 22nd, 2017

Pulses of electrons manipulate nanomagnets and store information: Scientists use electron pulses to create and manipulate nanoscale magnetic excitations that can store data July 21st, 2017

Semiliquid chains pulled out of a sea of microparticles July 20th, 2017

Imaging

Scientists announce the quest for high-index materials: All-dielectric nanophotonics: The quest for better materials and fabrication techniques July 22nd, 2017

Coupling a nano-trumpet with a quantum dot enables precise position determination July 14th, 2017

Laboratories

Studying Argon Gas Trapped in Two-Dimensional Array of Tiny "Cages": Understanding how individual atoms enter and exit the nanoporous frameworks could help scientists design new materials for gas separation and nuclear waste remediation July 17th, 2017

News laser design offers more inexpensive multi-color output: Design can control color, intensity of light by varying cavity architecture July 11th, 2017

Argonne National Laboratorys Continuous ALD Technology Licensed Exclusively to Forge Nano July 7th, 2017

Govt.-Legislation/Regulation/Funding/Policy

Ultrathin device harvests electricity from human motion July 23rd, 2017

The first light atomic nucleus with a second face July 20th, 2017

Semiliquid chains pulled out of a sea of microparticles July 20th, 2017

Here's a tip: Indented cement shows unique properties: Rice University models reveal nanoindentation can benefit crystals in concrete July 20th, 2017

Chip Technology

Semiliquid chains pulled out of a sea of microparticles July 20th, 2017

A firefly's flash inspires new nanolaser light July 18th, 2017

GLOBALFOUNDRIES and VeriSilicon To Enable Single-Chip Solution for Next-Gen IoT Networks: Integrated solution leverages GFs 22FDX technology to decrease power, area, and cost for NB-IoT and LTE-M applications July 14th, 2017

Nanometrics to Announce Second Quarter Financial Results on August 1, 2017 July 14th, 2017

Memory Technology

Pulses of electrons manipulate nanomagnets and store information: Scientists use electron pulses to create and manipulate nanoscale magnetic excitations that can store data July 21st, 2017

A firefly's flash inspires new nanolaser light July 18th, 2017

Giant enhancement of electromagnetic waves revealed within small dielectric particles: Scientists have done for the first time direct measurements of giant electromagnetic fields July 8th, 2017

Picosuns ALD solutions enable novel high-speed memories June 27th, 2017

Discoveries

Scientists announce the quest for high-index materials: All-dielectric nanophotonics: The quest for better materials and fabrication techniques July 22nd, 2017

Pulses of electrons manipulate nanomagnets and store information: Scientists use electron pulses to create and manipulate nanoscale magnetic excitations that can store data July 21st, 2017

The first light atomic nucleus with a second face July 20th, 2017

Semiliquid chains pulled out of a sea of microparticles July 20th, 2017

Announcements

Ultrathin device harvests electricity from human motion July 23rd, 2017

The July 23 close fly-by of asteroid 2017 BS5 is explored in a Q&A with Dr. John S. Lewis, chief scientist at Deep Space Industries July 23rd, 2017

Scientists announce the quest for high-index materials: All-dielectric nanophotonics: The quest for better materials and fabrication techniques July 22nd, 2017

Pulses of electrons manipulate nanomagnets and store information: Scientists use electron pulses to create and manipulate nanoscale magnetic excitations that can store data July 21st, 2017

Tools

Scientists announce the quest for high-index materials: All-dielectric nanophotonics: The quest for better materials and fabrication techniques July 22nd, 2017

Coupling a nano-trumpet with a quantum dot enables precise position determination July 14th, 2017

Nanometrics to Announce Second Quarter Financial Results on August 1, 2017 July 14th, 2017

Nanometrics Introduces SpectraProbe Analysis Software: Advanced software and algorithms enhancing Nanometrics metrology fleet capabilities fab-wide July 13th, 2017

Research partnerships

Studying Argon Gas Trapped in Two-Dimensional Array of Tiny "Cages": Understanding how individual atoms enter and exit the nanoporous frameworks could help scientists design new materials for gas separation and nuclear waste remediation July 17th, 2017

Coupling a nano-trumpet with a quantum dot enables precise position determination July 14th, 2017

GLOBALFOUNDRIES and VeriSilicon To Enable Single-Chip Solution for Next-Gen IoT Networks: Integrated solution leverages GFs 22FDX technology to decrease power, area, and cost for NB-IoT and LTE-M applications July 14th, 2017

Carbon displays quantum effects July 13th, 2017

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project