磁学实验室学术报告（2017-2）

来源：admin 发布时间：2018-01-15

Characterisation of the Surface Skyrmions in Chiral Magnets by

Resonant Elastic Soft X-Ray Scattering

时间：2017年12月19日 14:00

地点：中科院物理所M253

报告人：张石磊博士

Department of Physics, University of Oxford

摘要：
Magnetic skyrmions are magnetisation swirls that present topological properties, leading to a number of novel physics,

such as emergent electromagnetism and non-trivial magnetic dynamics. The prototypical skyrmion-hosting materials are

chiral magnets, such as MnSi, FeCoSi, FeGe and Cu₂OSeO₃, in which the long-range ordered skyrmion lattice is found

as the bulk state. Depending on the material, the individual skyrmion size in chiral magnets falls in the range of 3-100 nm.

Here, I present our recent results on charactering the skyrmion structures in such length-scale, using resonant elastic x-ray

scattering (REXS). Unlike neutrons or hard x-rays scattering, we utilise long wavelength, small attenuation-length soft x-ray

beam as the probe. This leads to considerably large scattering cross-section for 3d and rare-earth magnetic elements, better

reciprocal space resolution, as well as excellent surface sensitivity. First, I will show that the surface skyrmions behave

unexpectedly different from that is found in the bulk. It presents multidomain state, and strong surface-pinning effect.

Both effects are favoured by device applications. Second, I will demonstrate that REXS is able to reconstruct the very fine

internal structure of an individual skyrmion, inaccessible to other magnetic characterisation techniques. This allows us to

accurately measure the microscopic interactions of the material system. Lastly, I will show an in-situ REXS measurement

by applying a magnetic field gradient, under which the skyrmions undergo concentric rotation with well-defined slow dynamics.

This provides an effective way of controlling the skyrmions towards the racetrack memory embodiment.

简介:
2011年毕业于北京科技大学，2016年获英国牛津大学理学博士学位。

2016-今英国牛津大学物理系，博士后

在国际SCI收录的Nature Communication, Nano Letter, Phys. Rev.B 等重要学术期刊发表论文30余篇，引用220余次。

研究领域：

Neutron and x-ray scattering, magnetic spectroscopy

邀请人：王文洪研究员 (82649247)