Magnetic skyrmions-bubble hybrids in nanolayers of metallic ferromagnets: interplay of the magnetodipolar and Dzyaloshinskii-Moriya interactions

由本征和/或诱导Dzyaloshinskii-Moriya （DM）相互作用（手性skyrmions）稳定的轴对称孤子和由表面退磁效应稳定的普通圆柱形磁畴（气泡）是在最近合成的纳米层和多层磁性化合物堆中观察到的两种根本不同的拓扑非平凡磁结构。它们包含在纳米到微尺度的点上的反向磁化区域，因此被认为是新型磁数据存储和新兴自旋电子学中其他应用的有前途的对象。最近，在许多类型的纳米层中观察到一种不同类型的局部磁模式-在手性DM和磁偶极相互作用的共同影响下形成的。这些特定的局域态代表了在非中心对称铁磁体纳米层中发现的“纯”手性skyrmions和在具有强垂直各向异性的铁磁薄膜中产生的经典气泡域之间的中间物体。这些结构可以被认为是“skyrmions -bubble杂化体”，具有手性skyrmions和磁畴的特性。在这个项目中，我们将发展一个相应的局部和调制状态的理论，这些状态出现在最近合成的纳米磁系统中，具有中等或弱的垂直各向异性和由于DM相互作用而产生的固有和/或诱导手性调制。分析理论研究将结合使用高分辨率磁光克尔显微镜和全尺寸先进微磁模拟的领域观察。基于我们的理论和实验发现，我们打算对现代纳米磁性材料中产生的具有内在和诱导手性相互作用的气泡-斯基米子态进行全面的物理描述。

Axisymmetric solitons stabilized by intrinsic and/or induced Dzyaloshinskii-Moriya (DM) interactions (chiral skyrmions) and common cylindrical magnetic domains (bubbles) stabilized by surface demagnetization effects are two fundamentally different types of topologically non-trivial magnetic structures observed in recently synthesized nanolayers and multilayer stacks of magnetic compounds. They contain areas of reversed magnetization localized in spots of the nano- to microscale size and thus are considered as promising objects for novel types of magnetic data storage and other applications in emerging spin electronics. Recently, a different kind of localized magnetic patterns – formed under the combined influence of chiral DM and magnetodipolar interactions – has been observed in many types of nanolayers. These specific localized states represent intermediate objects between "pure" chiral skyrmions found in nanolayers of non-centrosymmetric ferromagnets and classical bubble domains arising in ferromagnetic films with strong perpendicular anisotropy. These structures can be considered as "skyrmion-bubble hybrids" exhibiting properties attributed both to chiral skyrmions and magnetic domains. Within this project we shall develop a theory of corresponding localized and modulated states arising in recently synthesized nanomagnetic systems with moderate or weak perpendicular anisotropy and intrinsic and/or induced chiral modulations due to the DM interaction. Analytical theoretical research will be combined with domain observation using high-resolution magneto-optical Kerr microscopy and full-scale advanced micromagnetic simulations. Based on our theoretical and experimental findings we intend to create a comprehensive physical description of the bubble-skyrmion states arising in modern nanomagnetic materials with intrinsic and induced chiral interactions.