题目

Novel physics in strongly spin-orbit coupled materials: Iridium alloys and oxides

报告人

Dr. Hua Chen

Department of Physics,

University of Texas at Austin, USA　　　　　　　　　　　　　

时间

2014年7月24日（星期四）上午10：00

地点

微尺度国家实验室9004会议室

Hua Chen received his B.S. degree from Zhengzhou University in 2006 and Ph.D degree from Department of Physics and Astronomy, the University of Tennessee at Knoxville in 2012.  Since then, he works as a postdoctoral fellow in theoretical and computational condensed matter physics at the University of Texas at Austin. His research interests are complex insulators and metals with strong spin-orbit coupling, berry-phase modified semiclassical electron dynamics, transport and spintronics, graphene growth and functionality, topological insulator heterostructures, heterogeneous catalysis and diluted magnetic semiconductors.

报告摘要

Spin-orbit coupling is one of the most interesting concepts in condensed matter physics. Anomalous Hall effect is one example of the many concequencies of spin-orbit coupling. Conventional wisdom assumes that the anomalous Hall effect is proportional to the net magnetization of a material. However, using simple symmetry arguments and first-principles calculations, we counter this assumption and find that a commonly used noncollinear antiferromagnet, Mn3Ir, has a large anomalous Hall conductivity, despite the vanishing of its total magnetization. Separately, 5d transition metal oxides as a new class of materials have attracted much attention in recent years. Among them, the perovskite-related Iridium oxides have been found to have exotic spin-orbital coupled ground states due to the strong atomic spin-orbit coupling of Ir. We developed effective superexchange models for two different Iridates, Sr2IrO4 and CaIrO3, and find the contrasting magnetic hysteresis behaviors of the two materials can be explained by their different local geometries combined with strong spin-orbit coupling.