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储鹏关于skyrmion的文章在SR发表


P. Chu, Y. L. Xie, Y. Zhang, J. P. Chen, D. P. Chen, Z. B. Yan, and J.-M. Liu(刘俊明)


Real-space anisotropic dielectric response in a multiferroic skyrmion lattice


Scientific Reports 5, 8318 (2015)


我们实验室对skyrmion及其点阵形成与物理机制的关注实际上很早,但一直未有任何拿得出手的结果与进展,这是令人遗憾的地方。这是我们经常置身其中的状况,体现了我们总是准备不足。原地打转的局面依然故我。

国内对skyrmion的研究基本局限在理论与模拟层面,开展实验研究的条件或者人员并不充分,因此国内有关成果发布基本都在理论层面上。当Y. Tokura在各种会议上侃侃而谈他们的漂亮实验结果时、当A.Fert他们在一再宣示skyrmion运动的电影时,我们除了赞叹之外也不知道如何去做。

目前skyrmion的观测无非是洛伦兹电镜方法,好像国内清华大学朱静院士等有这样的配置。由于skyrmion独特的实空间自旋拓扑结构,要看到其存在依然是技术上的挑战。一个好的准粒子如果不能被方便地看到与跟踪,其应用大概也就无从谈起。

我们一直都对非共线自旋结构与铁电极化的关系心有戚戚,因此skyrmion的非共线自旋结构与铁电性之间的对应应该是很自然的物理。这是我们做这个计算工作的基本动机。

如果真的可以发展一种介电探测技术来显示skyrmion及其点阵,应该是很有意义的。这一工作的缺点是需要测量微波介电。

但是,即便如此,作为一个理论方案,也许这一工作有一些参考价值。

A magnetic skyrmion lattice is a microstructure consisting of hexagonally aligned skyrmions. While a skyrmion as a topologically protected carrier of information promises a number of applications, an easily accessible probe of the skyrmion and skyrmion lattice at mesoscopic scale is of significance. It is known that neutron scattering, Lorentz transmission electron microscopy, and spin-resolved STM as effective probes of skyrmions have been established. In this work, we propose that the spatial contour of dielectric permittivity in a skyrmion lattice with ferromagnetic interaction and in-plane (xy) Dzyaloshinskii-Moriya (DM) interaction can be used to characterize the skyrmion lattice. The phase field and Monte Carlo simulations are employed to develop the one-to-one correspondence between the magnetic skyrmion lattice and dielectric dipole lattice, both exhibiting the hexagonal symmetry. Under excitation of in-plane electric field in the microwave range, the dielectric permittivity shows the dumbbell-like pattern with the axis perpendicular to the electric field, while it is circle-like for the electric field along the z-axis. The dependences of the spatial contour of dielectric permittivity on external magnetic field along the z-axis and dielectric frequency dispersion are discussed.

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