报告题目：Linear and second order response in topological semimetals 主讲嘉宾：孙岩博士（Max Planck Institute for Chemical Physics of Solids） 活动时间：1月9日（周三）上午10:00—11：30 活动地点：师昌绪楼403会议室 报告简介： We have found that the strong spin Hall effect in TaAs is mainly dominated from the Weyl points and nodal-line-like Fermi surface, which implying a strong interplay between the topological band structure and Berry curvature in topological semimetals. With this guiding principle, we have successfully understood the strong spin Hall effect in IrO2 and found the nodal line band structures in it. This principle was further verified by our developed database. Generalizing this principle to time reversal symmetry breaking system, we haveproposed strong anomalous Hall effect in magnetic Weyl semimetal Co3Sn2S2.Owing to the low charge carrier density and large Berry curvature from the nodal line band structure, the anomalous Hall conductivity and anomalous Hall angle experimentally reach up to 1130 S/cm and 20% respectively. Further, the anomalous Hall effect can even exist with zero net moments in the absence of the symmetry operation that changes the sign of Berry curvature. And the anomalous Hall effect can be strongly enhanced by the special band structures of Weyl points and nodal lines. Following this guiding direction, we have predicted a strong anomalous Hall effect in the compensated ferrimagneticWeyl semimetal Ti2MnAl and noncollinear antiferromagnetic Weyl metal Mn3Gewith vanishingnet magnetic moments. Our work is helpful for the comprehensive understanding of the linear response effect in topological materials and their future applications. Owing to the symmetry, some linear response effect is forbidden, but the higher order response can exist. We have studied the Berry curvature dipole and photogalvanic effect in inversion symmetry breaking systems, where anomalous Hall effect is forbidden by time reversal symmetry, but the second order responses can be enhanced by special electronical band structures. 嘉宾简介： 孙岩：博士，2009~2014年就读于中国科学院金属研究所，获博士学位。2014年至2017年1月在德国马普固体物理化学研究所从事博士后研究。2017年2月作为研究组长留在马普固体物理化学研究所工作。研究兴趣和领域主要包括拓扑材料和磁性材料的理论研究，线性响应和二阶响应对材料输运性能的影响和Berry phase effect。主要代表性工作有理论预测第一个被实验证实的type-II Weyl semimetal MoTe2，Weyl semimetal中的自旋霍尔效应，反铁磁材料中的反常霍尔和反常Nerst效应，建立了本征自旋霍尔效应的完整数据库。 欢迎所内职工和研究生前来交流！ | 