東北大学 · 物理学・天文学
Y. Saito教授の研究室は、金属材料の微細組織の発達挙動をシミュレーションと実験の両面から解明する研究を展開しています。特に、粒状成長における界面エネルギーの異方性や不純物・界面状態の影響が微細組織と物性(磁気抵抗、磁性相関など)に与える影響を、モンテカルロシミュレーションやイオンビームスパッタリングを用いて解明しています。また、多層膜系における界面化学組成や応力状態が巨大磁気抵抗効果に与える寄与をNMRや磁気測定を組み合わせて分析しています。
Figures are computed from collected data and may differ slightly.
Thetemporal evolution and morphology of two-dimensional grain growth are simulated by Monte Carlo simulation techniques. In the simulation, the anisotropy of the grain boundary energy is incorporated into the model. Compared with the case in which no anisotropy of boundary energy is assumed,the suppression of grain growth is observed and the grain size and the edge number distributions become broad. The occurrence of the wetting phenomena is considered to be responsible for the broadness of the
We have investigated the magnetic and magnetotransport properties of (Co x Fe 1- x /Cu) multilayers prepared by ion beam sputtering. We found that (Co x Fe 1- x /Cu) multilayers are new ones with large magnetoresistance in the range between x =0.6 and 1.0. We also found that the 27.2% magnetoresistance ratio could be observed for the magnetic field under the 0.9 kOe when (FeCo 9 10 Å/Cu10 Å) 15 was deposited on the MgO(110) single-crystal substrates. In this system, saturation field H s decrease
In relation to theoretical predictions on the importance of randomness at the interface to determine the cause for giant magnetoresistance, argon acceleration voltage (VB) in ion beam sputtering was changed for preparing a set of CoxFe1−x/Cu multilayers. We found that the magnetoresistance as quite sensitive to the argon acceleration voltage and had a maximum around VB=600 V. Perfect antiferromagnetic coupling of the CoxFe1−x layers via thin Cu layers and the oscillation behavior of this indirec
The temporal evolution and morphology of grain growth in three dimensions were simulated by Monte Carlo method. In order to prevent impingement of grains of like orientation, new algorithm was adopted. The anisotropy of the grain boundary energy is incorporated into the model. Compared with the case in which no anisotropy of boundary energy is assumed, the suppression of grain growth was observed at the initial stage of growth in the grain structure with anisotropic grain boundary energy. Howeve
The computer simulation model of microstructural evolution on the basis of chemical thermodynamics and classical nucleation and growth theory has been developed. The metallurgicai phenomena in thermomechanical treatment of steel, such as austenite grain growth, recrystallization and growth, carbonitride precipitation and austenite to ferrite phase transformation can be predicted by the model. The influences of steel chemistry and thermomechanical condition on the transformed microstructure of 0.
Co/Cu superlattices were prepared by changing the Ar acceleration voltage ( V B ) in ion beam sputtering. V B dependence on the nanostructure of the interface alloy regions has been deduced from the 59 Co nuclear magnetic resonance (NMR) spin-echo spectrum, and the correlation between the magnetoresistance (MR) ratio and interface structure was investigated. The results have shown that there is a correlation between the interlayer interaction and the interface chemical structure. The Co average
Local magnetoresistance (MR) through silicon (Si) and its bias voltage (Vbias) (bias current (Ibias)) dependence in ferromagnet (FM)/MgO/silicon-on-insulator lateral spin valves are investigated. From the experimental measurements, we find that the local-MR through Si increases with increasing Vbias. This anomalous increase of local-MR as a function of Vbias can be understood by considering the standard drift-diffusion theory improved by taking into account the difference in the interface resist
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