One of important challenges in condensed-matter physics is to realize new quantum states of matter by manipulating the dimensionality of materials,as represented by the discovery of high-temperature superconductivity ...One of important challenges in condensed-matter physics is to realize new quantum states of matter by manipulating the dimensionality of materials,as represented by the discovery of high-temperature superconductivity in atomic-layer pnictides and room-temperature quantum Hall effect in graphene.Tran sition-metal dichalcogenides(TMDs)provide a fertile platform for exploring novel quantum phenomena accompanied by the dimensionality change,since they exhibit a variety of electronic/magnetic states owing to quantum confinement.Here we report an anomalous metal-i nsulator transition in duced by three-dimensional(3D)-two-dimensional(2D)crossover in mono layer 1T-VSe2 grown on bilayer graphene.We observed a complete insulating state with a finite energy gap on the entire Fermi surface in monolayer 1T-VSe2 at low temperatures,in sharp contrast to metallic nature of bulk.More surprisingly,monolayer 1T-VSe2 exhibits a pseudogap with Fermi arc at temperatures above the charge-density-wave temperature,showing a close resemblanee to high-temperature cuprates.This similarity suggests a common underlying physics between two apparently different systems,pointing to the importance of charge/spin fluctuations to create the novel electronic states,such as pseudogap and Fermi arc,in these materials.展开更多
文摘One of important challenges in condensed-matter physics is to realize new quantum states of matter by manipulating the dimensionality of materials,as represented by the discovery of high-temperature superconductivity in atomic-layer pnictides and room-temperature quantum Hall effect in graphene.Tran sition-metal dichalcogenides(TMDs)provide a fertile platform for exploring novel quantum phenomena accompanied by the dimensionality change,since they exhibit a variety of electronic/magnetic states owing to quantum confinement.Here we report an anomalous metal-i nsulator transition in duced by three-dimensional(3D)-two-dimensional(2D)crossover in mono layer 1T-VSe2 grown on bilayer graphene.We observed a complete insulating state with a finite energy gap on the entire Fermi surface in monolayer 1T-VSe2 at low temperatures,in sharp contrast to metallic nature of bulk.More surprisingly,monolayer 1T-VSe2 exhibits a pseudogap with Fermi arc at temperatures above the charge-density-wave temperature,showing a close resemblanee to high-temperature cuprates.This similarity suggests a common underlying physics between two apparently different systems,pointing to the importance of charge/spin fluctuations to create the novel electronic states,such as pseudogap and Fermi arc,in these materials.
