Crystal growth and magnetism of novel low-dimensional van der Waals materials

新型低维范德华材料的晶体生长和磁性

• 批准号: 447482487
• 负责人: Professor Dr. Bernd Büchner
• 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/447482487?language=en
• 关键词: Crystal; growth; magnetism; novel; low

Magnetic van der Waals (vdW) compounds have emerged by virtue of a very weak vdW interlayer coupling as an ideal platform for realization of two-dimensional (2D) spin networks and as such have attracted significant attention both in fundamental research on 2D magnetism as well as regarding applications in the next generation of spin-electronic devices. New intriguing magnetic properties are predicted in these materials, such as unusual types of magnetic order, exotic spin liquid phases and unconventional magnetic excitations. The flexibility of the chemical composition and structural variability offer a handle to tune in a controllable way magnetic parameters of these compounds in a broad range and thus to experimentally realize the theoretically predicted phases with desired characteristics. In our project we propose to grow high quality single crystals of new layered magnetic vdW materials and explore their static and dynamic magnetic properties using sub-THz high-field ESR (HF-ESR) spectroscopy and complementary static magnetometry methods. We will start with the exploratory synthesis of new single-crystalline materials along several routes, perform their comprehensive analytical characterization and study static magnetic properties to determine the size of the magnetic moment, the ordering temperature, and the type of order. This should give a feedback for optimization of material synthesis and provide input for spectroscopic HF-ESR studies. Since ESR spectroscopy is very sensitive to magnetic anisotropies which enter in directly measurable quantities, such as the g-factor tensors and energy gaps for the ESR excitations, this method emerges as an instructive tool to investigate magnetic phases of the synthesized new vdW compounds. We will use the advantages of the HF-ESR instrumentation at the IFW Dresden which enables 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 at temperatures down to 300 mK. Systematic studies of frequency, magnetic field, and orientation 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 low-energy spin dynamics and to relate these parameters with the chemical composition and crystallographic structure. An important aspect of the project will be studies of exfoliated samples to investigate the dependence of magnetic properties on the sample thickness. The obtained information should enable to classify the studied materials with respect to the theoretically proposed magnetic phases and should help to verify theoretical models of 2D vdW compounds.

磁性范德华（vdW）化合物由于非常弱的vdW层间耦合而出现，作为实现二维（2D）自旋网络的理想平台，因此在二维磁性的基础研究以及下一代自旋电子器件的应用中都引起了极大的关注。在这些材料中预测了新的有趣的磁性，如不寻常类型的磁序，奇特的自旋液相和非常规的磁激发。化学成分的灵活性和结构的可变性为在大范围内以可控的方式调整这些化合物的磁性参数提供了一个把手，从而在实验上实现具有所需特性的理论预测相。在我们的项目中，我们建议使用亚太赫兹高场ESR （HF-ESR）光谱和互补的静态磁强计方法来生长高质量的新型层状磁性vdW材料单晶，并研究其静态和动态磁性能。我们将从探索性合成新的单晶材料开始，沿着几种路线，对其进行综合分析表征，并研究静态磁性能，以确定磁矩的大小，有序温度和有序类型。这将为材料合成的优化提供反馈，并为光谱HF-ESR研究提供输入。由于ESR光谱对直接可测量量的磁各向异性非常敏感，例如g因子张量和ESR激发的能隙，因此该方法成为研究合成的新vdW化合物的磁相的指导性工具。我们将使用HF-ESR仪器的优点在德累斯顿IFW使高灵敏度检测ESR信号在很宽的频率范围从0.01到1太赫兹领域16 T,在温度下降到300可。系统的研究频率、磁场,和方向依赖性的ESR模式将允许单个水晶样品准确测定磁各向异性,在基态自旋结构,低能自旋动力学参数，并将这些参数与化学成分和晶体结构联系起来。该项目的一个重要方面将是研究剥离样品，以调查磁性能对样品厚度的依赖。获得的信息应该能够根据理论上提出的磁相对所研究的材料进行分类，并有助于验证二维vdW化合物的理论模型。