Domain wall motion and spin wave-量子物質科學協同創新中心

報告題目： Domain wall motion and spin wave 報告人： Xiang-Rong Wang The Hong Kong University of Science and Technology 報告時間： 11月29日（星期五）下午2:30 報告地點：物理系三樓報告廳摘要： 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. 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. Our studies imply that two DWs can interact with other through the SWs. 報告人簡介： Prof. Wang obtained his B.Sc. degree (1984) from Wuhan University and Ph. D. degree (1990) from the University of Rochester. He joined the Physics Department of HKUST in 1992. Prof. Wang is working in the field of theoretical condensed matter physics and statistical physics. His main research interests include spintronics, metal-insulator transitions and quantum Hall effect; mesoscopic physics in hopping and variable-range hopping conductions; nonlinear electron transport in superlattices, quantum wires and quantum dots; quantum entanglements and quantum computation; novel properties in nano-structures; and critical phenomena.