Static and dynamic magnetism of topologically non-trivial magnetic materials

拓扑非平凡磁性材料的静态和动态磁性

• 批准号: 499461434
• 负责人: Dr. Alexey Alfonsov, Ph.D.
• 金额: --
• 依托单位: Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden (IFW) e.V.
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/499461434?language=en
• 关键词: Static; dynamic; magnetism; topologically; non

The topology of the electronic bands has shown its importance in the field of condensed matter physics by paving a way to a discovery of new states of matter such as topological insulators (TI). Strong spin-orbit coupling present in this class of materials causes a non-triviality of the bulk band topology, which, in turn, yields a massless Dirac dispersion with spin-momentum locking at the surface. The recent discovery of magnetic topological insulators (MTI) has opened new avenues to explore exotic phenomena, such as the quantum anomalous Hall effect, the topological magnetoelectric effect and chiral Majorana fermions, which can emerge from the interplay between topological electronic states and magnetic degrees of freedom, be they ordered or strongly fluctuating. A very informative method to study the latter is high-field high-frequency electron spin resonance (ESR) spectroscopy complemented with static magnetometry technique. In our project, we propose to use ESR spectroscopy to obtain new comprehensive insights into the fundamental origin and the details of the magnetism in MTIs, and to establish a relation of the magnetic properties such as magnetic anisotropy, interactions and ordering with observed signatures of the non-trivial band topology. We will use the advantages of the high-field high-frequency ESR instrumentation at the IFW Dresden enabling a high-sensitivity detection of ESR signals in a very broad frequency range from 0.01 to 1 THz, in fields up to 16 T, and in a temperature range 0.3 - 300 K. Systematic studies of frequency, magnetic field, and angular dependences of the ESR modes in single-crystalline samples will allow an accurate determination of the magnetic anisotropies, the spin structures in the ground state, and parameters of the spin dynamics. The accurate evaluation of the temperature dependences of the ESR response grants access to the dynamics of the magnetic moments, thereby allowing the investigation of the interplay between electronic structure and fluctuating magnetic moments in the paramagnetic state. We will relate all these parameters with the chemical composition, crystallographic structure, and with the observed features of the non-trivial band topology in the studied MTIs. An important aspect of the project will be studies of exfoliated samples, which will enable the investigation of the thickness dependent evolution of the surface dominated magnetism. The obtained information should be of a paramount importance for a comprehensive understanding of the nature of the static and dynamic magnetism in both, ordered and not ordered, states of magnetic topological insulators, which is necessary for further assessment of the interplay between magnetism and non-trivial band topology.

电子能带的拓扑结构在凝聚态物理学领域显示出其重要性，为发现拓扑绝缘体（TI）等新的物质状态铺平了道路。这类材料中存在的强自旋-轨道耦合导致了体能带拓扑的非平凡性，这反过来又产生了表面处具有自旋-动量锁定的无质量狄拉克色散。最近发现的磁性拓扑绝缘体（MTI）开辟了新的途径来探索奇异的现象，如量子反常霍尔效应，拓扑磁电效应和手征马约拉纳费米子，它可以出现在拓扑电子态和磁自由度之间的相互作用，无论它们是有序的还是强烈的波动。一个非常翔实的方法来研究后者是高场高频电子自旋共振（ESR）光谱补充静态磁力技术。在我们的项目中，我们建议使用ESR光谱，以获得新的全面的见解的基本起源和细节的磁性在MTIs，并建立一个关系的磁性能，如磁各向异性，相互作用和排序与观察到的签名的非平凡带拓扑结构。我们将利用IFW Dresden的高场高频ESR仪器的优势，在0.01至1 THz的非常宽的频率范围内，在高达16 T的磁场中，在0.3 - 300 K的温度范围内，实现ESR信号的高灵敏度检测。系统研究单晶样品中ESR模式的频率、磁场和角度依赖性，将允许精确确定磁各向异性、基态自旋结构和自旋动力学参数。ESR响应的温度依赖性的准确评估赠款访问的磁矩的动态，从而允许在顺磁状态下的电子结构和波动的磁矩之间的相互作用的调查。我们将把所有这些参数与化学组成、晶体结构以及所研究的MTI中观察到的非平凡能带拓扑特征联系起来。该项目的一个重要方面将是剥离样品的研究，这将使厚度依赖的表面主导的磁性演变的调查。所获得的信息应该是一个至关重要的静态和动态磁性的性质，有序和不有序的，状态的磁性拓扑绝缘体，这是必要的进一步评估之间的相互作用的磁性和非平凡带拓扑的全面了解。