| Co-Investigator(Kenkyū-buntansha) |
YONENAGA Ichiro Tohoku Univ., Institute of Metals, Research Associate, 金属材料研究所, 助教授 (20134041)
TOMITA Yukihiro National Institute for Fusion Science, Associate Professor, 理論・シミュレーション研究センター, 助教授 (40115605)
SATOH Motoyasu National Institute for Fusion Science, Professor, 大型ヘリカル研究部, 教授 (60115855)
OGAWA Isamu Fukui Univ., Associate Professor, 工学部, 助教授 (90214014)
TSUSHIMA Akira Yokohama National Univ., Associate Professor, 工学部, 助教授 (90171991)
OKUMURA Haruhiko Matsusaka Univ., Professor
HASEGAWA Yasuhiro Saitama Univ.
|
|---|
| Research Abstract |
We study the magnetic field effect on Bismuth-Antimony (BiSb) single crystal in this fiscal year. BiSb was studied in the early 1960's by many researchers, and the positive result of the magnetic field effect was reported. Electric resistance is increased, thermal conduction is reduced and the Seebeck coefficient is increased, and finally the figure of merit is twice under magnetic field. This improvement is relative large, but this effect is not used in the present time. In 1990's, Japanese researchers reported that the magnetic field effect is negative and the figure of merit is not increased under any magnetic field. In order to resolve the discrepancy, we study the magnetic field effect for BiSb again. There are two types of effects under magnetic field, one is "microscopic effect", and the other is "macroscopic effect". At first we focus to study the macroscopic effect that is defined by the generalized Ohm's law and its correspondent heat flux density equation. We developed the two-dimensional calculation code for arbitrary shape of sample and its electrode system. We compared with the calculation and experimental results for the magnetoresitance, and we find the good accordance of the results in various shapes of the samples. We also compared the Seebeck coefficients, and also find the good accordance. These analysis can separate the microscopic and macroscopic effects, and the Seebeck coefficient is affected by the Hall and Nersnt coefficients. Our final conclusion for the discrepancy depends on the shape of the samples and their electrodes, and if we choose a good shape of sample and electrode, we can observe the increase of the figure of merit under magnetic field.
We also proceed the design of Peltier Current Lead (PCL) in this fiscal year. The computer code for PCL is developed and this will be used to fix the optimum design and data analysis.
|
