Using angle-resolved photoemission spectroscopy and density functional theory calculations methods,we investigate the electronic structures and topological properties of ternary tellurides NbIrTe_(4),a candidate for t...Using angle-resolved photoemission spectroscopy and density functional theory calculations methods,we investigate the electronic structures and topological properties of ternary tellurides NbIrTe_(4),a candidate for type-II Weyl semimetal.We demonstrate the presence of several Fermi arcs connecting their corresponding Weyl points on both termination surfaces of the topological material.Our analysis reveals the existence of Dirac points,in addition to Weyl points,giving both theoretical and experimental evidences of the coexistence of Dirac and Weyl points in a single material.These findings not only confirm NbIrTe_(4) as a unique topological semimetal but also open avenues for exploring novel electronic devices based on its coexisting Dirac and Weyl fermions.展开更多
At least four two-or quasi-one-dimensional allotropes and a mixture of them were theoretically predicted or experimentally observed for low-dimensional Te,namely theα,β,γ,δ,and chiral-α+δphases.Among them theγ...At least four two-or quasi-one-dimensional allotropes and a mixture of them were theoretically predicted or experimentally observed for low-dimensional Te,namely theα,β,γ,δ,and chiral-α+δphases.Among them theγandαphases were found to be the most stable phases for monolayer and thicker layers,respectively.Here,we found two novel low-dimensional phases,namely theεandζphases.Theζphase is over 29 meV/Te more stable than the most stable monolayerγphase,and theεphase shows comparable stability with the most stable monolayerγphase.The energetic difference between theζandαphases reduces with respect to the increased layer thickness and vanishes at the four-layer(12-sublayer)thickness,while this thickness increases under change doping.Bothεandζphases are metallic chains and layers,respectively.Theζphase,with very strong interlayer coupling,shows quantum well states in its layer-dependent bandstructures.These results provide significantly insight into the understanding of polytypism in Te few-layers and may boost tremendous studies on properties of various few-layer phases.展开更多
Topological materials have attracted extensive attention in condensed matter physics because of their exotic physical properties and promising potential applications.If the bulk gap of an insulator closes at certain n...Topological materials have attracted extensive attention in condensed matter physics because of their exotic physical properties and promising potential applications.If the bulk gap of an insulator closes at certain nodal points or lines in the Brillouin zone(BZ),the resultant gapless phase is known as the topological semimetal(TSM)[1].Dirac nodal line semimetals(DNLSMs)[2,3]have been sought as novel quantum materials presenting quantum anomalies[4,5].The DNLSMs against spin-orbit coupling(SOC)were discovered in several three-dimensional(3D)bulk materials[6–8].Flourishing two-dimensional(2D)van der Waals(vdW)materials are,in comparison with their 3D counterparts,easier to experimentally measure and manipulate.However,2D materials have one less dimension of translation symmetry operation,and the corresponding symmetry operations and groups are significantly reduced,narrowing the range of candidate structures.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos.12274455,12274459,and 12204533)the National Key R&D Program of China (Grant No.2022YFA1403800)the Beijing Natural Science Foundation (Grant No.Z200005)。
文摘Using angle-resolved photoemission spectroscopy and density functional theory calculations methods,we investigate the electronic structures and topological properties of ternary tellurides NbIrTe_(4),a candidate for type-II Weyl semimetal.We demonstrate the presence of several Fermi arcs connecting their corresponding Weyl points on both termination surfaces of the topological material.Our analysis reveals the existence of Dirac points,in addition to Weyl points,giving both theoretical and experimental evidences of the coexistence of Dirac and Weyl points in a single material.These findings not only confirm NbIrTe_(4) as a unique topological semimetal but also open avenues for exploring novel electronic devices based on its coexisting Dirac and Weyl fermions.
基金Project supported by the Science Fund from the Ministry of Science and Technology(MOST)of China(Grant No.2018YFE0202700)the National Natural Science Foundation of China(Grant Nos.11274380,91433103,11622437,61674171,11974422,and 61761166009)+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB30000000)the Fundamental Research Funds for the Central Universities of China and the Research Funds of Renmin University of China(Grant No.16XNLQ01)the Research Grant No.Council of Hong Kong,China(Grant No.N_PolyU540/17)the Hong Kong Polytechnic University(Grant No.G-SB53).Cong Wang was supported by the Outstanding Innovative Talents Cultivation Funded Programs 2017 of Renmin University of China.
文摘At least four two-or quasi-one-dimensional allotropes and a mixture of them were theoretically predicted or experimentally observed for low-dimensional Te,namely theα,β,γ,δ,and chiral-α+δphases.Among them theγandαphases were found to be the most stable phases for monolayer and thicker layers,respectively.Here,we found two novel low-dimensional phases,namely theεandζphases.Theζphase is over 29 meV/Te more stable than the most stable monolayerγphase,and theεphase shows comparable stability with the most stable monolayerγphase.The energetic difference between theζandαphases reduces with respect to the increased layer thickness and vanishes at the four-layer(12-sublayer)thickness,while this thickness increases under change doping.Bothεandζphases are metallic chains and layers,respectively.Theζphase,with very strong interlayer coupling,shows quantum well states in its layer-dependent bandstructures.These results provide significantly insight into the understanding of polytypism in Te few-layers and may boost tremendous studies on properties of various few-layer phases.
基金financial support from the Ministry of Science and Technology(MOST)of China(2018YFE0202700,2017YFA0302903,and 2019YFA0308603)the National Natural Science Foundation of China(11622437,61674171,61761166009,11574392,11974421,11974422,11774422,12174443,and 12134020)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(XDB30000000)the Fundamental Research Funds for the Central Universities,and the Research Funds of Renmin University of China(22XNKJ30(W.J.)and 21XNH090(D.P.G.))。
文摘Topological materials have attracted extensive attention in condensed matter physics because of their exotic physical properties and promising potential applications.If the bulk gap of an insulator closes at certain nodal points or lines in the Brillouin zone(BZ),the resultant gapless phase is known as the topological semimetal(TSM)[1].Dirac nodal line semimetals(DNLSMs)[2,3]have been sought as novel quantum materials presenting quantum anomalies[4,5].The DNLSMs against spin-orbit coupling(SOC)were discovered in several three-dimensional(3D)bulk materials[6–8].Flourishing two-dimensional(2D)van der Waals(vdW)materials are,in comparison with their 3D counterparts,easier to experimentally measure and manipulate.However,2D materials have one less dimension of translation symmetry operation,and the corresponding symmetry operations and groups are significantly reduced,narrowing the range of candidate structures.
