报告题目：One decade of topological magnetic solitons: from 1D to 3D

报告人：王宪思 博士（挪威科技大学）

邀请人：董帅

时间： 2020年1月7日下午2点

地点： 田家炳楼南205会议室

摘要： Since S. Parkin proposed and demonstrated the “domain wall racetrack memory” in 2008, the investigation on topological magnetic solitons has attracted boosting attention. The basic idea is to utilize the topological magnetic solitons as information carriers and manipulate them in a desired way. During the last decade, many proposals for manipulation of 1D solitons (domain walls) and 2D solitons (vortices and skyrmions) have been revealed, and each of them has its own advantages and disadvantages. A natural question is whether there exist 3D topological magnetic solitons, and if so, how is their dynamics. We studied the current-driven dynamics of 3D topological magnetic solitons called magnetic hopfions. We find that, in ferromagnetic materials, two types of hopfions, Bloch-type and Néel-type hopfions, can be excited as metastable states in the presence of bulk and interfacial Dzyaloshinskii-Moriya interactions, respectively. We further investigate how hopfions can be driven by currents via spin-transfer torques (STTs) and spin-Hall torques (SHTs). Distinct from 2D ferromagnetic skyrmions, hopfions have a vanishing gyrovector. Consequently, there are no undesirable Hall effects. Néel-type hopfions move along the current direction via both STT and SHT, while Bloch-type hopfions move either transverse to the current direction via SHT or parallel to the current direction via STT. Our findings add 3D hopfions into the family of magnetic-soliton information carriers besides 1D domain walls and 2D vortices/skyrmions, with their unique advantage.

报告人简介：王宪思，2010年本科毕业于中国科学技术大学少年班系，2015年博士毕业于香港科技大学物理系，之后先后在香港科技大学、电子科技大学、挪威科技大学进行博士后研究。研究方向主要为磁动力学和自旋电子学理论。