报告时间：2018年3月16日下午4点

报告地点：近代物理系210会议室

报告人：南京大学 缪冰锋副教授

报告题目：Hybrid Magnetic Skyrmions

报告摘要：Skyrmions show great potential for future information technology due to their small size and to the small current densities needed to displace them. Fundamentally, skyrmion is of particular interest as it carries a topological charge and Berry phase in real space and is anticipated to produce unconventional spin-electronic phenomena.

Typically, skyrmions emerge from the Dzyaloshinskii–Moriya interaction (DMI) in a finite magnetic field, at low temperature (natural skyrmion materials). Alternatively, a growing group of artificially designed magnetic superstructures allowing for the existence of skyrmions without the need for a microscopically built-in DMI mechanism (artificial skyrmion materials). Artificial skyrmions significantly expand the phase diagram, and has been demonstrated at room temperature and in the absence of magnetic field. The mobility of the artificial skyrmion, however, is restricted by the patterned disks.

Here, we present a novel design of building on the advantages of both the natural and the artificial skyrmion materials from the available skyrmion physics toolbox. We demonstrate that this is possible, and we denote the emerging novel material as hybrid magnetic skyrmions (HMS). The proposed HMS can be driven by an electrical current to a speed of 850 m/s. We further demonstrate the viability of information encoding and propagation with the HMS in a nano-track. With a high current pulse, isolated skyrmions can be created individually due to the spin transfer torque. With a low steady current, the skyrmions can then be driven with relatively high speed. As individual skyrmions can be detected by a simple Hall geometry via the topological Hall effect, the proposed hybrid structure allows the construction of the HMS racetrack memory that can work at higher temperature and with higher speed compared to skyrmion stabilized by the DMI with the same magnitude only. Our approach pave a new pathway of material engineering for the skrymion-based applications.

References:

[1] H. Z. Wu, B. F. Miao, L. Sun, D. Wu, and H. F. Ding, Phys. Rev. B 95, 174416 (2017).

[2] B. F. Miao, L. Sun, Y. W. Wu, et.al., Phys. Rev. B 90, 174411 (2014).

[3] L. Sun, R. X. Cao, B. F. Miao, etal., Phys. Rev. Lett. 110, 167201 (2013).