Transition metal dichalcogenides are layered materials which are composed of transition metals and chalcogens of the group VIA in a 1:2 ratio. These layered materials have been extensively investigated over synthesis and optical and electrical properties for several decades. It can be insulators, semiconductors, or metals revealing all types of condensed matter properties from a magnetic lattice distorted to superconducting characteristics. Some of these also feature the topological manner. Instead of covering the semiconducting properties of transition metal dichalcogenides, which have been extensively revisited and reviewed elsewhere, here we present the structures of metallic transition metal dichalcogenides and their synthetic approaches for not only high-quality wafer-scale samples using conventional methods (e.g., chemical vapor transport, chemical vapor deposition) but also local small areas by a modification of the materials using Li intercalation, electron beam irradiation, light illumination, pressures, and strains. Some representative band structures of metallic transition metal dichalcogenides and their strong layer-dependence are reviewed and updated, both in theoretical calculations and experiments. In addition, we discuss the physical properties of metallic transition metal dichalcogenides such as periodic lattice distortion, magnetoresistance, superconductivity, topological insulator, and Weyl semimetal. Approaches to overcome current challenges related to these materials are also proposed.

中文翻译：

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范德华金属过渡金属硫属元素化物

过渡金属二卤化物是层状材料，由过渡金属和VIA组硫族元素按1：2的比例组成。这些层状材料已在合成，光学和电学性能方面进行了数十年的广泛研究。它可以是绝缘体，半导体或金属，它们可以显示出从扭曲的磁晶格到超导特性的所有类型的冷凝物特性。其中一些还具有拓扑方式。在此，我们将介绍金属过渡金属二卤化物的结构及其合成方法，该方法不仅适用于使用常规方法（例如，化学蒸气输送，化学气相沉积），还可以通过使用锂插层，电子束辐照，光照，压力和应变对材料进行改性来改变局部小区域。在理论计算和实验中，对金属过渡金属二卤化物的一些代表性能带结构及其强的层依赖性进行了综述和更新。此外，我们讨论了金属过渡金属二卤化物的物理特性，例如周期性晶格畸变，磁阻，超导性，拓扑绝缘体和Weyl半金属。还提出了克服与这些材料有关的当前挑战的方法。在理论计算和实验中，对金属过渡金属二卤化物的一些代表性能带结构及其强的层依赖性进行了综述和更新。此外，我们讨论了金属过渡金属二卤化物的物理特性，例如周期性晶格畸变，磁阻，超导性，拓扑绝缘体和Weyl半金属。还提出了克服与这些材料有关的当前挑战的方法。在理论计算和实验中，对金属过渡金属二卤化物的一些代表性能带结构及其强的层依赖性进行了综述和更新。此外，我们讨论了金属过渡金属二卤化物的物理特性，例如周期性晶格畸变，磁阻，超导性，拓扑绝缘体和Weyl半金属。还提出了克服与这些材料有关的当前挑战的方法。拓扑绝缘体和Weyl半金属。还提出了克服与这些材料有关的当前挑战的方法。拓扑绝缘体和Weyl半金属。还提出了克服与这些材料有关的当前挑战的方法。