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 value added to the ICSD (Inorganic Crystal Structure Database)
27.03.2017 | FIZ Karlsruhe – Leibniz-Institut für Informationsinfrastruktur GmbH
Argon is not the 'dope' for metallic hydrogen
24.03.2017 | Carnegie Institution for Science
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
27.03.2017 | Earth Sciences
27.03.2017 | Life Sciences
27.03.2017 | Life Sciences