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Topological solitons in two-dimensional chiral magnets

二维手性磁体中的拓扑孤子

基本信息

批准号：
321131738
负责人：
Professor Dr. Christof Erich Melcher
金额：
--
依托单位：
Lehrstuhl I für Mathematik (für Ingenieure)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/321131738?language=en
关键词：
Topological solitons two dimensional chiral

项目摘要

Chiral skyrmions are topological field configurations occurring in magnets of broken chiral symmetry. These novel magnetic nanostructures emerge as isolated solitons or arranged in regular lattices, which amounts to a new magnetic order in the style of the vortex state in superconductivity. Chiral skyrmions have been predicted theoretically about 25 years ago on the basis of a remarkably simple energy functional. The key effect is chirality induced Dzyaloshinskii-Moriya interaction, which is the anti-symmetric counterpart of Heisenberg exchange and expressed in terms of helicity type functionals. The unexpected recent experimental discovery of chiral skyrmions in a variety of material systems has boosted the interest and activity and opened a new direction in physics. Owing to their outstanding stability properties and efficient dynamic coupling to electric currents, chiral skyrmions became a promising candidate as information carrier in future spintronic devices.The project is concerned with the formation, structure and dynamics of topological patterns arising from chiral interaction in the spatially two-dimensional context. We shall address the occurrence and stability of skyrmionic structures in models of chiral magnets by means of global variational calculus. A major challenge we shall meet is the comprehensive understanding of the governing phase diagram. The current theoretical prediction is mainly based on numerical minimization of the energy functional or ad-hoc optimization of a specific Ansatz. Therefore a global mathematical approach to rigorously characterize critical fields would be desirable. With improved knowledge on the energetics and internal structure of isolated chiral skyrmions, we aim to examine the dynamic stability and effective dynamics arising from the Landau-Lifshitz-Gilbert equation coupled to spin- torque effects. We expect that the mathematical insight achieved and methods developed within this project will also contribute to the exploration of new aspects in the physics of chiral skyrmions and to the search of new mechanisms to stabilize topological solitons in magnetism.

手征skyrmions是发生在手征对称性破缺的磁体中的拓扑场构型。这些新颖的磁性纳米结构以孤立的孤子或规则的晶格排列出现，相当于超导涡旋态风格的新磁序。手征skyrmions已在理论上预测约25年前的基础上一个非常简单的能量泛函。关键效应是手性诱导的Dzyaloshinskiii-Moriya相互作用，它是海森堡交换的反对称对应物，并以螺旋度型泛函表示。近年来，手性Skyrmions在各种物质体系中的意外发现，极大地激发了人们对手性Skyrmions的兴趣和研究热情，并为物理学开辟了一个新的方向。由于手性Skyrmion具有良好的稳定性和与电流的有效动力学耦合，使其成为未来自旋电子器件中信息载体的一个很有前途的候选者。本项目主要研究在二维空间背景下手性相互作用所产生的拓扑图案的形成、结构和动力学。我们将通过整体变分法讨论手征磁体模型中skyrmionic结构的出现和稳定性。我们将遇到的一个主要挑战是全面理解控制相图。目前的理论预测主要是基于数值最小化的能量泛函或ad-hoc优化的一个特定的Ancestor。因此，一个全球性的数学方法，严格的关键领域的特点将是可取的。随着对孤立手征Skyrmions的能量学和内部结构的进一步了解，我们的目标是研究与自旋矩效应耦合的Landau-Lifshitz-吉尔伯特方程的动力学稳定性和有效动力学。我们期望在这个项目中实现的数学洞察力和开发的方法也将有助于探索手征skyrmions物理学的新方面，并寻找新的机制来稳定磁拓扑孤子。