Magnetic materials that enhance the magnetotransport property and for the high-density/low-power consumption magnetic memory
Skyrmion and skyrmion molecule a: Skyrmion The arrows indicate the directions of the electron spins. The electron spins in a skyrmion head toward the center, while spinning in a vortex shape. The spin directions at the center and at the outermost periphery are vertically opposite. b: Schematic diagram of a skyrmion molecule c: Skyrmion molecule observed within a ferromagnetic thin film in an experiment The plus and minus signs respectively indicate clockwise and counterclockwise spin direction.
While the current density required for driving domain walls within a ferromagnetic system is about 1 billion amperes per square meter, they managed to drive those skyrmion molecules with one-thousandth that density . This result was achieved by a joint research group led by Dr. Xiuzhen Yu, Senior Research Scientist, and Dr. Yoshinori Tokura, Group Director (Professor at the School of Engineering, the University of Tokyo) of the Strong Correlation Physics Research Group, RIKEN Center for Emergent Matter Science (Center Director: Dr. Yoshinori Tokura), and Dr. Koji Kimoto, Unit Director of the Surface Physics and Structure Unit, Advanced Key Technologies Division (Division Director: Dr. Daisuke Fujita), NIMS.
Magnetic memory devices, which use the direction of electron spins within materials as magnetic information, are considered to be promising next-generation devices with high-speed and non-volatile properties. In recent years, magnetic memory devices that manipulate domain walls within ferromagnetic nanowires by using spin polarized electric current have been intensively studied. However, moving domain walls requires a large current density of at least about 1 billion amperes per square meter, and the large power consumption presented a problem. Therefore, a way to drive them under smaller current density had been sought.
In this respect, attention has been paid to "skyrmions," which are magnetic topological textures in which electron spins are aligned in a vortex shape. Unlike ferromagnetic domain walls, skyrmions have no intrinsic pinning sites and can avoid obstacles in the device. Thus, they can be driven under smaller current density than ferromagnetic domain walls. A single skyrmion has topological charge 1, which is equivalent to 1 bit of information. Skyrmions with higher topological charge had been predicted theoretically, but they had never been actually observed.
The joint research group succeeded for the first time in generating skyrmion molecules with topological charge 2 in layered manganese oxide La1+2xSr2-2xMn2O7 while controlling the uniaxial anisotropy and the externally-applied magnetic field, and in driving them with one-thousandth the current density conventionally required for driving ferromagnetic domain walls. Such findings will bring about great development in designing novel magnetic memory devices with high-density and low power consumption with use of skyrmions. The research result has been published in the online edition of the British science journal Nature Communications on January 25 (January 26 JST).
For more details
Dr. Xiuzhen Yu
Senior Research Scientist, Strong Correlation Physics Research Group, RIKEN Center for Emergent Matter Science, RIKEN
TEL: +81-48-462-1111(ext 6324)
Dr. Yoshinori Tokura
Professor, School of Engineering, the University of Tokyo
Group Director, Strong Correlation Physics Research Group,
Center Director, RIKEN Center for Emergent Matter Science, RIKEN
Public relations staff
Emergent Matter Science Planning Office
New material could advance superconductivity
28.07.2016 | Carnegie Institution for Science
Dirty to drinkable
27.07.2016 | Washington University in St. Louis
Transparent electronics devices are present in today’s thin film displays, solar cells, and touchscreens. The future will bring flexible versions of such devices. Their production requires printable materials that are transparent and remain highly conductive even when deformed. Researchers at INM – Leibniz Institute for New Materials have combined a new self-assembling nano ink with an imprint process to create flexible conductive grids with a resolution below one micrometer.
To print the grids, an ink of gold nanowires is applied to a substrate. A structured stamp is pressed on the substrate and forces the ink into a pattern. “The...
A new Fraunhofer MEVIS method conveys medical interrelationships quickly and intuitively with innovative visualization technology
On the monitor, a brain spins slowly and can be examined from every angle. Suddenly, some sections start glowing, first on the side and then the entire back of...
Researchers at the U.S. Department of Energy's (DOE) Ames Laboratory have discovered an unusual property of purple bronze that may point to new ways to achieve high temperature superconductivity.
While studying purple bronze, a molybdenum oxide, researchers discovered an unconventional charge density wave on its surface.
Munich Physicists have developed a novel electron microscope that can visualize electromagnetic fields oscillating at frequencies of billions of cycles per second.
Temporally varying electromagnetic fields are the driving force behind the whole of electronics. Their polarities can change at mind-bogglingly fast rates, and...
Breakup of continents with two speed: Continents initially stretch very slowly along the future splitting zone, but then move apart very quickly before the onset of rupture. The final speed can be up to 20 times faster than in the first, slow extension phase.phases
Present-day continents were shaped hundreds of millions of years ago as the supercontinent Pangaea broke apart. Derived from Pangaea’s main fragments Gondwana...
29.07.2016 | Event News
15.07.2016 | Event News
15.07.2016 | Event News
29.07.2016 | Power and Electrical Engineering
29.07.2016 | Life Sciences
29.07.2016 | Event News