Research Achievements 2010 | Tohoku University Global COE Program - Materials Integration -

Research Results 2010 (List)
Sep.	Spin-Seebeck effect in insulators and insulator-based thermoelectric generationf (Saitoh Lab., IMR)
Sep.	Final Conclusion is Achieved on the Mechanism of Magnetism by Supercomputer (Kawazoe Lab., IMR)
July	Development of a new nanocrystalline soft magnetic material exhibiting ultra low electric power loss and high magnetic flux density, toward practical applications (Makino Lab., IMR)
June	Enhanced output power in ZnO Ultraviolet Light Emitting Diodes (Kawasaki Lab., WPI)
April	Crystal lenses focusing X-rays with an over 100 gain. - possible to simultaneous analyses of several elements - (Nakjima Lab., IMR)
March	Ultimate structure and composition of lithium niobate (LiNbO3) for superior optical properties (Uda Lab., IMR)
March	Spin current and electric signal transmission in insulator (Saitoh Lab., IMR)

Spin-Seebeck effect in insulators and insulator-based thermoelectric generation

Sep.2010 Surface and Interface Research group (Saitoh Group), in collaboration with Japan Atomic Energy Agency, FDK Corporation, Delft University of Technology in the Netherlands, and Fudan University in China, has discovered that a spin-Seebeck effect, generation of spin currents as a result of temperature differences, appears in magnetic insulators, which has been measured only in ferromagnetic metals. Furthermore, the group has showed that, by combining this phenomenon with the relativity effect in a solid (inverse spin-Hall effect), thermoelectric power can be generated from heat flowing in an insulator, which has seemed to be impossible. The achievement would enable the use of insulators, with less energy loss due to heat transfer, for thermoelectric conversion elements, which could result in widening design possibilities and installation sites of such elements and contribute to environment-friendly electric technologies. This work was performed as a part of the research programs of New Energy and Industrial Technology (NEDO) and Japan Science and Technology Agency (JST). The research result was published in the scientific journal gNature Materialsh as an Advanced Online Publication (September 27, 2010), and was reported in news papers of Nikkan Kogyo Shimbun and Denki Shimbun. Saitoh Lab., IMR

Final Conclusion is Achieved on the Mechanism of Magnetism by Supercomputer

Sep.2010 Recently strong magnets are widely used from electric vehicle to wall-pin magnet. However, although model theories and so-called ab initio calculations have been used to explain magnetism, it was very difficult to establish reliable guideline to design unknown magnetic materials without experimental or model parameters, because of complexity of quantum mechanical many-body problem. Prof. Kawazoefs group has conducted a large scale theoretical calculation using the supercomputer SR11000 of the Center for Computational Materials Science for second and third row atoms with electron correlation satisfying accurately virial theorem. The origin of the Hundfs first and second rules is successfully confirmed to mainly be the attractive interaction between nucleus and spin aligned electrons, and contribution from exchange energy is small, even reversed assumed in the perturbation theory of Prof. Slater. These research results will be published in the September issue of The Journal of Chemical Physics, and was reported Nikkan-Kogyo Newspaper on 16th September. Kawazoe Lab., IMR

Development of a new nanocrystalline soft magnetic material exhibiting ultra low electric power loss and high magnetic flux density, toward practical applications

July 2010 The research group of Professor Makino at Advanced Research Center of Metallic glasses has developed a new nano-crystalline soft magnetic material composed of ~95 mass% Fe without rare-earth metals. The new low-cost soft magnetic material exhibits high magnetic flux density (1.8~1.9T) along with extremely low core-losses (1/2~1/3 of the ordinary materials). The group is also collaborating with various companies for its practical applications in transformer cores, electric motors, choke coils etc.. Currently, electrical power loss resulting from the magnetic core-losses in motors and transformers is estimated to be 3.4% of the total domestic electrical power consumption, that accounts for more than 2% of total CO2 emissions. High magnetic flux density silicon steel is the most widely used core material over 100 years, and further reduction in core-loss seems to be impossible. In view of increasing demands of high efficiency and high performance electric motors for hybrid/electrical-vehicles (HEV/EV), the development of new low core-loss materials is extremely important. The new nano-material developed in Professor Makino's group is expected to not only contribute in reduction of CO2 emission but also be useful from the perspective of conserving the Earth's resources. The research achievements are scheduled as an invited talk at the 55th Annual Conf. on Magnetism and Magnetic Materials which will be held in Atlanta, USA from 14~18 November. The related articles have already appeared 7 time in newspapers; Nikkei, Nikkan Kogyo (twice), Nikkei Sangyo (twice), Chemical Industry Sinbun and kahoku shimpo from 20 May to 28 July. Makino Lab., IMR

Enhanced output power in ZnO Ultraviolet Light Emitting Diodes

June 2010 Superstructured Thin Film Chemistry group (M. Kawasaki group) has successfully enhanced the output power of ZnO light emitting diodes under the collaboration with RHOM Co. Ltd. and IMRAM Tohoku University. The devices were made with molecular beam epitaxy technique on conducting ZnO substrates, which are suitable choices for mass production.@It is expected to pave a way for low-cost, high-efficiency, and energy-saving illumination. This result has become public in Applied Physics Letters (online publication) on July 6th. Such press sources as Nikkei-Sangyo, Nikkan-Kogyou (June 30) and Kahoku-Shinpo (July 2) introduced the achievement. Kawasaki Lab., WPI

Crystal lenses focusing X-rays with an over 100 gain. - possible to simultaneous analyses of several elements -

April 2010 Prof. K. Nakajimafs lab. (Crystal Physics), Assoc. Prof. Hayashi (Chemical Physics of Non-Crystalline Materials) and Kyoto University group have successfully developed two types of X-ray crystal lenses, which can realize industrial-strength X-ray apparatuses. These lenses were fabricated using their hot deformation technique, which can form a Si or Ge crystal into an arbitrary 3D shape. Applying these lenses to commercially available X-ray sources, we can obtain X-ray beams over one hundred times stronger than those from conventional X-ray optics. This feature enables us to carry out a real time X-ray analysis in in-house experiment, like experiments at huge synchrotron radiation facilities, such as SPring-8, and this will assist the understanding of chemical states during some reactions of materials. This work was performed as a part of the Programs of Japan Science and Technology Agency (JST) gDevelopment of Systems and Technology for Advanced Measurement and analysish. The research achievement was published in the Japanese Science Journal "Appl. Phys. Express" on March 19, 2010, and was presented at the 57th Spring Meeting of the Japan Society of Applied Physics. Moreover, it was broadcasted in Miyagi TV news program (March 30, 2010), and was introduced in Kahoku Shimpo (April 1, 2010), Kagaku Shimbun (April 23, 2010). Nakajima Lab., IMR

Ultimate structure and composition of lithium niobate (LiNbO3) for superior optical properties

March 2010 Prof. S. Udafs lab. (Crystal Chemistry group) and Prof. Taniuchi of Center for Interdisciplinary Research have successfully developed a new single crystal of LiNbO3 (lithium niobate: LN) addressed as cs-MgO:LN. This was invented by the intentional introduction of an impurity (MgO) and defect (vacancy) to LN crystal that makes a LN crystal congruent with stoichiometric structure. cs-MgO:LN is very easy to grow and shows superior optical properties over the conventional LNs, particularly in their homogeneities. cs-MgO:LN is used as a frequency conversion device in low dimensions and is a potential candidate for pure green color source for a large display, medical instruments and measurement hardware for physical properties. The research result was presented at the 57th Spring Meeting of the Japan Society of Applied Physics, and published in newspaper (Kagaku Kogyo Nippou, on March 11, 2010). Uda Lab., IMR

Spin current and electric signal transmission in insulator

March 2010 Surface and Interface Research group (Saitoh Group), in collaboration with Theory of Solid State Physics group (Maekawa group), Magnetic Materials group (Takanashi group), Keio University and FDK Corporation, has successfully demonstrated that a spin current can be injected into a Mott insulator and can propagate over a long distance. Furthermore, the group has showed that even an insulator can transmit electric signals via these processes. This has enabled, for the first time, to use spin current in insulator, making a good use of the relativity effect in a solid (spin-Hall effect) and exchange interaction at the interface between a metal and a Mott insulator. It would lead to the developments of new signal transmission devices with low energy dissipation. This work was performed as a part of the Basic Research Programs of Japan Science and Technology Agency (JST). The research achievement was published in the British Science Journal "Nature" on March 11, 2010, and was reported in the top pages of Mainichi Shimbun, Kahoku Shimpo (March 11, 2010), and others. Saitoh Lab., IMR