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