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Theory of chiral modulations in confining structures: epitaxial films of cubic helimagnets

限制结构中的手性调制理论：立方螺旋磁体的外延膜

基本信息

批准号：
240641318
负责人：
Professor Dr. Alexei N. Bogdanov
金额：
--
依托单位：
Institut für Theoretische Festkörperphysik
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2014
资助国家：
德国
起止时间：
2013-12-31 至 2017-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/240641318?language=en
关键词：
Theory chiral modulations confining structures

项目摘要

Recently synthesized epitaxial thin films of cubic helimagnets with non-centrosymmetric B20 structure (MnSi, FeGe, and others) represent a novel class of nanomagnetic systems exhibiting many physical phenomena unknown in bulk helimagnets. In particular, nanolayers of cubic helimagnets enable the observation of specific particle-like structures (skyrmions) predicted theoretically more than twenty years ago and the field-induced unwinding of helicoids via quantized steps. Our recent studies show that in nanolayers of cubic helimagnets the interplay between intrinsic chirality, structural confinement, and surface/interface induced interactions leads to the formation of specific confined chiral modulations which fundamentally differ from those commonly observed in bulk helimagnets. The aim of the project is to give a comprehensive theoretical description of confined chiral modulations and, thus, to establish physical relations between specific effects arising in cubic helimagnet nanolayers and peculiarities of their structures. Within the standard micromagnetic theory of helimagnetism rigorous solutions for helical and skyrmionic modulations in thin layers of cubic helimagnets will be derived in broad ranges of the thermodynamic parameters. Our theoretical findings will be used to construct magnetic phase diagrams for nanolayers of cubic helimagnets with different types of induced magnetic anisotropy. These results will be applied for detailed analyses of recent experiments in epitaxial films of MnSi and FeGe and to elucidate complex magnetization processes observed in these systems. They also should provide the theoretical basis for the emerging nanophysics of confined chiral modulations and supply practical recommendations for future investigations.

最近合成的具有非中心对称B20结构的立方磁铁磁体外延薄膜(MnSi、FeGe等)代表了一类新型的纳米磁系统，它展示了许多体磁磁体中未知的物理现象。特别是，立方螺旋网的纳米层使人们能够观察到20多年前理论上预测的特定的类似粒子的结构(Skyrmions)，以及通过量子化步骤的场诱导螺旋面的解旋。我们最近的研究表明，在立方螺旋网的纳米层中，本征手性、结构约束和表面/界面诱导的相互作用导致了特定的受限手性调制的形成，这与通常在块状螺旋网中观察到的手性调制是根本不同的。该项目的目的是对受限手性调制进行全面的理论描述，从而建立立方螺旋网纳米膜中产生的特定效应与其结构特性之间的物理联系。在标准的日磁学微磁理论中，我们将在很宽的热力学参数范围内推导出立方螺旋磁网薄层中螺旋和天离子调制的严格解。我们的理论结果将被用来构建具有不同类型感生磁各向异性的立方磁力网纳米层的磁相图。这些结果将用于详细分析最近在MnSi和FeGe外延薄膜中的实验，并阐明在这些系统中观察到的复杂磁化过程。它们还应该为限制手性调制的新兴纳米物理提供理论基础，并为未来的研究提供实用建议。