报告人:Prof. X. R. Wang (The Hong Kong University of Science and Technology)

时间: 2012年09月12日(星期三) 下午 14:30

地点: 中国科学院半导体研究所学术沙龙

 Abstract: In this talk, I will discuss the interplay between magnetic domain wall (DW) motion and spin waves (SW). Both DW and SW are the fundamental excitations of magnetic systems. In a magnetic nanowire, we show that DW propagation accompanies normally spin wave emission on the one hand. On the other hand, a SW passing through a DW tends to drive the DW moving against the SW propagating direction. This interplay between DW and SW leads to very rich physics. Following recent discovery will be presented: 1) Magnon, quanta of SW, can efficiently mediate spin angular momentum transfer between SW and DW because magnons are spin-1 particles.2) Magnonic spin-transfer torque can drive a DW to propagate at a high speed. 3) DW motion will generate SW, and, as a result, a static magnetic field can even drive a DW to propagate along a dissipationless nanowire through SW emission. 4) The widely believed Walker rigid-body propagation mode is not stable in a dissipated wire because of the SW emission, and DW propagation is locked into a soliton mode. Furthermore, our studies imply that two DWs can interact with other through the SWs.

 报告人简介：王向荣，香港科技大学终身教授；1984年毕业于武汉大学物理系，同年通过中美联合招收物理研究生选拨考试(CUSPEA) 赴美深造；1990年在美国罗彻斯特大学(University of Rochester)获博士学位；多年来致力于香港内地科研合作，是山东大学、武汉大学、北京师范大学、中科院固体物理研究所等多所学校和研究机构的客座教授，同时担任中科院物理研究所理论与计算部的顾问委员。研究方向：在凝聚态理论领域具有丰富研究经验，研究领域包括量子霍尔效应，二维电子气量子输运，超晶格以及量子纠缠与量子计算；创造性地提出了超晶格中电流自振荡的极限环理论；从理论上揭示了磁动力学中磁畴壁运动的机理，为完全理解磁畴壁的运动规律提供了理论基础；迄今已在国际权威学术杂志发表论文过百篇。