Charge Density Wave and Electron-Phonon Interaction in Epitaxial Monolayer NbSe$_{2}$ Films
About: This article is published in Chinese Physics Letters.The article was published on 2021-09-28 and is currently open access. It has received 6 citations till now. The article focuses on the topics: Monolayer & Charge density wave.
Citations
More filters
TL;DR: In this article , the phase transition between T- and H-H-VTe2 was revealed with X-ray photoelectron spectroscopy (XPS) and scanning transmission electron microscopy (STEM) measurements.
Abstract:
Charge density wave (CDW) strongly affects the electronic properties of two-dimensional (2D) materials and can be tuned by phase engineering. Among 2D transitional metal dichalcogenides (TMDs), H-VTe2 was predicted to require small energy for its phase transition and shows unexpected CDW states in its T-phase. However, the CDW state of H-VTe2 has been barely reported. Here, we investigate the CDW states in monolayer (ML) H-H-VTe2, induced by phase-engineering from T-phase H-VTe2. The phase transition between T- and H-H-VTe2 is revealed with X-ray photoelectron spectroscopy (XPS) and scanning transmission electron microscopy (STEM) measurements. For H-H-VTe2, scanning tunneling microscope (STM) and low-energy electron diffraction (LEED) results show a robust $2\sqrt{3}\times 2\sqrt{3}$ CDW superlattice with a transition temperature above 450 K. Our findings provide a promising way for manipulating the CDWs in 2D materials and show great potential in its application of nanoelectronics.
2 citations
TL;DR: In this article , the phase transition between T- and H-VTe2 was revealed with x-ray photoelectron spectroscopy (XPS) and scanning transmission electron microscopy (STEM) measurements.
Abstract: Charge density wave (CDW) strongly affects the electronic properties of two-dimensional (2D) materials and can be tuned by phase engineering. Among 2D transitional metal dichalcogenides (TMDs), VTe2 was predicted to require small energy for its phase transition and shows unexpected CDW states in its T-phase. However, the CDW state of H-VTe2 has been barely reported. Here, we investigate the CDW states in monolayer (ML) H-VTe2, induced by phase-engineering from T-phase VTe2. The phase transition between T- and H-VTe2 is revealed with x-ray photoelectron spectroscopy (XPS) and scanning transmission electron microscopy (STEM) measurements. For H-VTe2, scanning tunneling microscope (STM) and low-energy electron diffraction (LEED) results show a robust 23×23 CDW superlattice with a transition temperature above 450 K. Our findings provide a promising way for manipulating the CDWs in 2D materials and show great potential in its application of nanoelectronics.
2 citations
TL;DR: In this article , the lattice in-plane thermal transport of 2D NbSe2 was investigated by solving the phonon Boltzmann transport equation with the help of the first principles calculation.
Abstract: Niobium diselenide (NbSe2) is a layered transition metal dichalcogenide material which possesses unique electrical and superconducting properties for future nanodevices. While the superconducting, electrical, and bulk thermal transport properties of NbSe2 have been widely studied, the in-plane thermal transport property of NbSe2, which is important for potential thermoelectric applications, has not been thoroughly investigated. In this report, we study the lattice in-plane thermal transport of 2D NbSe2 by solving the phonon Boltzmann transport equation with the help of the first principles calculation. The thermal conductivity obtained at room temperature is 12.3 W/mK. A detailed analysis shows that the transverse acoustic phonon dominates the lattice thermal transport, and an anomalously small portion of electron contribution to the total thermal conductivity is observed for this metallic phase. The results agree well with experimental measurements and provide detailed mode-by-mode thermal conductivity contribution from different phonon modes. This study can provide useful information for integrating NbSe2 in nanodevices where both electrical and thermal properties are critical, showing great potential for integrating monolayer NbSe2 to thermoelectric devices.
[...]
TL;DR: In this article , Angle-Resolved Photoemission Spectroscopy (ARPES) is used to extract the spectral properties of a photoemission spectroscopy from a single image.
Abstract: 材料的电子结构是决定其电、磁、光等性质的关键因素，而能够直接观测材料电子结构的角分辨光电子能谱（Angle-Resolved Photoemission Spectroscopy，ARPES）技术是研究材料的基本物理和化学性质的先进技术手段之一。近年来，各种具有优异性能的二维材料被人们不断发掘出来，并有望成为未来光电、电子和自旋器件的基础材料。在本文中，我们将对ARPES的构成和原理做简要的介绍，并总结了当前利用ARPES技术研究二维材料电子结构及其基本物性的前沿进展。本文所关注的二维材料体系主要包含以下四个部分：石墨烯、氮化硼、单元素二维材料、过渡金属硫族化合物。其中对石墨烯的ARPES研究成果最为丰富，对它的研究直接引领了对其他二维材料的ARPES研究。当前，对基于不同二维材料相互堆叠形成的异质结构的研究正方兴未艾，我们在文中也提及一部分关于二维堆垛异质结构的ARPES研究。
References
More filters
TL;DR: In this article, the interaction of light with non-conducting crystals has been studied in the context of crystal lattices and its applications in general theory and applications, such as semi-conductivity and superconductivity.
Abstract: 1. Crystal lattices. General theory 2. . Crystal lattices. Applications 3. Interaction of light with non-conducting crystals 4. Electrons in a perfect lattice 5. Cohesive forces in metals 6. Transport phenomena 7. Magnetic properties of metals 8. Ferromagnetism 9. Interaction of light with electrons in solids 10. Semi-conductors and luminescence 11. Superconductivity
3,538 citations
TL;DR: In this article, the authors examined the methods used to synthesize transition metal dichalcogenides (TMDCs) and their properties with particular attention to their charge density wave, superconductive and topological phases, along with their applications in devices with enhanced mobility and with the use of strain engineering to improve their properties.
Abstract: Graphene is very popular because of its many fascinating properties, but its lack of an electronic bandgap has stimulated the search for 2D materials with semiconducting character. Transition metal dichalcogenides (TMDCs), which are semiconductors of the type MX2, where M is a transition metal atom (such as Mo or W) and X is a chalcogen atom (such as S, Se or Te), provide a promising alternative. Because of its robustness, MoS2 is the most studied material in this family. TMDCs exhibit a unique combination of atomic-scale thickness, direct bandgap, strong spin–orbit coupling and favourable electronic and mechanical properties, which make them interesting for fundamental studies and for applications in high-end electronics, spintronics, optoelectronics, energy harvesting, flexible electronics, DNA sequencing and personalized medicine. In this Review, the methods used to synthesize TMDCs are examined and their properties are discussed, with particular attention to their charge density wave, superconductive and topological phases. The use of TMCDs in nanoelectronic devices is also explored, along with strategies to improve charge carrier mobility, high frequency operation and the use of strain engineering to tailor their properties. Two-dimensional transition metal dichalcogenides (TMDCs) exhibit attractive electronic and mechanical properties. In this Review, the charge density wave, superconductive and topological phases of TMCDs are discussed, along with their synthesis and applications in devices with enhanced mobility and with the use of strain engineering to improve their properties.
3,436 citations
TL;DR: In this paper, the electronic and optical properties and the recent progress in applications of 2D semiconductor transition metal dichalcogenides with emphasis on strong excitonic effects, and spin- and valley-dependent properties are reviewed.
Abstract: The electronic and optical properties and the recent progress in applications of 2D semiconductor transition metal dichalcogenides with emphasis on strong excitonic effects, and spin- and valley-dependent properties are reviewed. Recent advances in the development of atomically thin layers of van der Waals bonded solids have opened up new possibilities for the exploration of 2D physics as well as for materials for applications. Among them, semiconductor transition metal dichalcogenides, MX2 (M = Mo, W; X = S, Se), have bandgaps in the near-infrared to the visible region, in contrast to the zero bandgap of graphene. In the monolayer limit, these materials have been shown to possess direct bandgaps, a property well suited for photonics and optoelectronics applications. Here, we review the electronic and optical properties and the recent progress in applications of 2D semiconductor transition metal dichalcogenides with emphasis on strong excitonic effects, and spin- and valley-dependent properties.
2,612 citations
TL;DR: A genome-wide association study in the Nordic region identifying a novel MM risk locus at ELL2 that encodes a stoichiometrically limiting component of the super-elongation complex that drives secretory-specific immunoglobulin mRNA production and transcriptional regulation in plasma cells is reported.
Abstract: Multiple myeloma (MM) is characterized by an uninhibited, clonal growth of plasma cells. While first-degree relatives of patients with MM show an increased risk of MM, the genetic basis of inherited MM susceptibility is incompletely understood. Here we report a genome-wide association study in the Nordic region identifying a novel MM risk locus at ELL2 (rs56219066T; odds ratio (OR)=1.25; P=9.6 × 10(-10)). This gene encodes a stoichiometrically limiting component of the super-elongation complex that drives secretory-specific immunoglobulin mRNA production and transcriptional regulation in plasma cells. We find that the MM risk allele harbours a Thr298Ala missense variant in an ELL2 domain required for transcription elongation. Consistent with a hypomorphic effect, we find that the MM risk allele also associates with reduced levels of immunoglobulin A (IgA) and G (IgG) in healthy subjects (P=8.6 × 10(-9) and P=6.4 × 10(-3), respectively) and, potentially, with an increased risk of bacterial meningitis (OR=1.30; P=0.0024).
1,342 citations
TL;DR: A combined optical and electrical transport study on the many-body collective-order phase diagram of NbSe2 down to a thickness of one monolayer opens up a new window for search and control of collective phases of two-dimensional matter, as well as expanding the functionalities of these materials for electronic applications.
Abstract: Enhanced electron–phonon interactions in mono- and few-layer NbSe2 result in a significantly increased transition temperature of charge density waves compared with values in the bulk.
704 citations