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岩崎 悠真*; 澤田 亮人*; Stanev, V.*; 石田 真彦*; 桐原 明宏*; 大森 康智*; 染谷 浩子*; 竹内 一郎*; 齊藤 英治; 萬 伸一*
npj Computational Materials (Internet), 5, p.103_1 - 103_6, 2019/10
被引用回数:47 パーセンタイル:87.54(Chemistry, Physical)Machine learning is becoming a valuable tool for scientific discovery. Particularly attractive is the application of machine learning methods to the field of materials development, which enables innovations by discovering new and better functional materials. To apply machine learning to actual materials development, close collaboration between scientists and machine learning tools is necessary. However, such collaboration has been so far impeded by the black box nature of many machine learning algorithms. It is often difficult for scientists to interpret the data-driven models from the viewpoint of material science and physics. Here, we demonstrate the development of spin-driven thermoelectric materials with anomalous Nernst effect by using an interpretable machine learning method called factorized asymptotic Bayesian inference hierarchical mixture of experts (FAB/HMEs). Based on prior knowledge of material science and physics, we were able to extract from the interpretable machine learning some surprising correlations and new knowledge about spin-driven thermoelectric materials. Guided by this, we carried out an actual material synthesis that led to the identification of a novel spin-driven thermoelectric material. This material shows the largest thermopower to date.
新見 康洋*; 木俣 基*; 大森 康智*; Gu, B.; Ziman, T.*; 前川 禎通; Fert, A.*; 大谷 義近*
Physical Review Letters, 115(19), p.196602_1 - 196602_5, 2015/11
被引用回数:12 パーセンタイル:62.87(Physics, Multidisciplinary)We have measured spin Hall effects in spin glass metals, CuMnBi alloys, with the spin absorption method in the lateral spin valve structure. Far above the spin glass temperature where the magnetic moments of Mn impurities are randomly frozen, the spin Hall angle of a CuMnBi ternary alloy is as large as that of a CuBi binary alloy. Surprisingly, however, it starts to decrease at about 4 and becomes as little as 7 times smaller at 0.5. A similar tendency was also observed in anomalous Hall effects in the ternary alloys. We propose an explanation in terms of a simple model considering the relative dynamics between the localized moment and the conduction electron spin.