Influence of interlayer interaction on the charge and lattice dynamics in layered transition-metal chalcogenides

点击翻译按钮获取中文摘要

Layered transition-metal chalcogenides exhibit a plethora of interesting physical properties and exotic phases due to competing correlation effects and topology, such as charge-density wave, Mott insulator, superconductivity, antiferromagnetic topological insulator, Weyl semimetal, and ferromagnetic nodal-line semimetal. Furthermore, they provide an ideal platform for realizing atomically thin, van der Waals crystals with unique properties and excellent prospects for novel applications. For the understanding of the physical properties of these novel 2D crystals, the characterization and understanding of their bulk physical properties is crucial as a preliminary step and is the subject of this project.One key aspect determining the physical properties of two-dimensional, layered materials is the interlayer interaction. In particular, the variation of the interlayer interaction by changing the van der Waals interlayer spacing greatly affects their physical properties and induces phase transitions with emerging exotic phases. The systematic study and understanding of the influence of the interlayer interaction on the charge and lattice dynamics in layered transition-metal chalcogenides are the goal of this project. External pressure is the most effective way for tuning the interlayer spacing and hence the interlayer interaction in a controlled manner. Hence, external pressure will be applied within this project to systematically investigate the influence of interlayer interaction on the charge and lattice dynamics. By pressure-dependent infrared and Raman spectroscopy the charge and lattice dynamics can be studied while tuning the interlayer interaction in layered materials. This way, the pressure-induced electronic changes and phase transitions with emerging exotic electronic phases can be monitored and characterized in detail and with a high energy resolution.As model systems for this study several layered transition-metal chalcogenides are chosen, which on the one hand show interesting physical properties already at ambient pressure such as Weyl semimetal or magnetic topological phase, and on the other hand are very sensitive regarding pressure application.