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三重简并拓扑半金属MoP中超快圆偏振光产生和调控光生热电流
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作者 加孜拉·哈赛恩 朱恪嘉 +3 位作者 孙飞 吴艳玲 石友国 赵继民 《物理学报》 SCIE EI CAS CSCD 北大核心 2020年第20期112-118,共7页
超快激光可以用来产生和调控拓扑量子材料中的拓扑相变和自旋极化电流,这些光诱导产生的新奇物性源于材料中受到体系对称性保护的线性色散能带结构的简并节点.作为一种同时具有两重和三重简并节点的拓扑半金属,磷化钼(MoP)是一类非常独... 超快激光可以用来产生和调控拓扑量子材料中的拓扑相变和自旋极化电流,这些光诱导产生的新奇物性源于材料中受到体系对称性保护的线性色散能带结构的简并节点.作为一种同时具有两重和三重简并节点的拓扑半金属,磷化钼(MoP)是一类非常独特的拓扑半金属体系.本文初步探索了三重简并拓扑半金属晶体MoP中产生自旋极化电流和奇异光学响应的机理,设计并搭建了以圆偏振光产生并调控光电流的实验装置.首先采用该装置成功在拓扑绝缘体Bi2Se3中产生了光电流,与国际上已报道的实验结果对比效果很好,证明了实验装置的可行性和可靠性;进而对MoP进行了同样的光电流产生与调控实验.采用400 nm的圆偏振超快激光脉冲,在样品不同位置成功观测到了电流信号,分析认为其为热电流,不是与三重简并拓扑特性相关的光电流.这为未来进一步产生和调控光电流提供了重要的研究基础,对于研究普遍的拓扑量子材料的光电流效应具有可借鉴的意义. 展开更多
关键词 光电流 三重简并拓扑材料 超快光谱 自旋极化
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Machine Learning to Instruct Single Crystal Growth by Flux Method
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作者 姚唐适 唐岑瑶 +11 位作者 杨萌 朱恪嘉 闫大禹 伊长江 冯子力 雷和畅 李承贺 王乐 王磊 石友国 孙煜杰 丁洪 《Chinese Physics Letters》 SCIE CAS CSCD 2019年第6期98-102,共5页
Growth of high-quality single crystals is of great significance for research of condensed matter physics. The exploration of suitable growing conditions for single crystals is expensive and time-consuming, especially ... Growth of high-quality single crystals is of great significance for research of condensed matter physics. The exploration of suitable growing conditions for single crystals is expensive and time-consuming, especially for ternary compounds because of the lack of ternary phase diagram. Here we use machine learning(ML) trained on our experimental data to predict and instruct the growth. Four kinds of ML methods, including support vector machine(SVM), decision tree, random forest and gradient boosting decision tree, are adopted. The SVM method is relatively stable and works well, with an accuracy of 81% in predicting experimental results. By comparison,the accuracy of laboratory reaches 36%. The decision tree model is also used to reveal which features will take critical roles in growing processes. 展开更多
关键词 MACHINE LEARNING Instruct Single CRYSTAL GROWTH FLUX Method
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From Claringbullite to a New Spin Liquid Candidate Cu_3Zn(OH)_6FCl
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作者 冯子力 衣玮 +7 位作者 朱恪嘉 魏源 苗杉杉 马杰 雒建林 李世亮 孟子杨 石友国 《Chinese Physics Letters》 SCIE CAS CSCD 2019年第1期70-74,共5页
The search for quantum spin liquid(QSL) materials has attracted significant attention in the field of condensed matter physics in recent years, however so far only a handful of them are considered as candidates hostin... The search for quantum spin liquid(QSL) materials has attracted significant attention in the field of condensed matter physics in recent years, however so far only a handful of them are considered as candidates hosting QSL ground state. Owning to their geometrically frustrated structures, Kagome materials are ideal systems to realize QSL. We synthesize the kagome structured material claringbullite(Cu_4(OH)_6FCl) and then replace inter-layer Cu with Zn to form Cu_3Zn(OH)_6FCl. Comprehensive measurements reveal that doping Zn^(2+) ions transforms magnetically ordered Cu_4(OH)_6FCl into a non-magnetic QSL candidate Cu_3Zn(OH)_6FCl. Therefore,the successful syntheses of Cu_4(OH)_6FCl and Cu_3Zn(OH)_6FCl provide not only a new platform for the study of QSL but also a novel pathway of investigating the transition between QSL and magnetically ordered systems. 展开更多
关键词 Clarinbrey STONE Cu3Zn(OH)6FCl QSL
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