机构地区:[1]Beijing National Laboratory for Condensed Matter Physics and Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China [2]Department of Physics,Southern University of Science and Technology,Shenzhen 518055,China [3]School of Physical Sciences,University of Chinese Academy of Sciences,Beijing 100049,China [4]School of Materials Science and Engineering,Anhui University,Hefei 230601,China [5]Laboratory for Neutron Scattering,and Beijing Key Laboratory of Optoelectronic Functional Materials MicroNano Devices,Department of Physics,Renmin University of China,Beijing 100872,China [6]Shanghai Synchrotron Radiation Facility,Shanghai Advanced Research Institute,Chinese Academy of Sciences,Shanghai 201204,China [7]Vacuum Interconnected Nanotech Workstation(Nano-X),Suzhou Institute of Nano-Tech and Nano-Bionics(SINANO),Chinese Academy of Sciences,Suzhou 215123,China [8]Songshan Lake Materials Laboratory,Dongguan 523808,China [9]CAS Center for Excellence in Topological Quantum Computation,University of Chinese Academy of Sciences,Beijing 100190,China
出 处:《Science Bulletin》2023年第2期165-172,M0003,共9页科学通报(英文版)
基 金:supported by the National Natural Science Foundation of China(U1832202,11888101,11920101005,12141402,and 12274459);the Chinese Academy of Sciences(QYZDB-SSW-SLH043,XDB33020100,and XDB28000000);the Beijing Municipal Science and Technology Commission(Z171100002017018,and Z200005);the National Key R&D Program of China(2018YFE0202600,2022YFA1403100,and 2022YFA1403800);the Fundamental Research Funds for the Central Universities and Research Funds of Renmin University of China(RUC)(18XNLG14,19XNLG13,19XNLG17,and 20XNH062);the Synergic Extreme Condition User Facility,Beijing,China;Beijing National Laboratory for Condensed Matter Physics。
摘 要:拓扑边界态出现在拓扑非平庸态和平庸态之间的边界上,通常是无间隙的或被称为金属态.例如,拓扑绝缘体的表面态是无间隙的狄拉克态.这些金属拓扑边界态往往可以被近自由费米子很好的描述.如果拓扑边界态具有显著的电子-电子相互作用的行为,无间隙的边界态会转变为有间隙的有序态,例如密度波态或超导态,这在理论上是非常有趣的,但目前还缺少相关的实验证据.本文报道了在Co Si(001)表面观察到了电子-电子相互作用驱动的、在拓扑边界态上形成的非公度电荷密度波(CDW). CDW的波矢随温度的变化而变化,这与拓扑表面费米弧随温度的演化相吻合. CDW相的取向由费米弧的手性决定,这暗示了CDW与费米弧之间存在直接的联系.该发现将促进在拓扑材料边界上寻找更多相互作用驱动的有序态,例如超导和磁性.Topological boundary states emerged at the spatial boundary between topological non-trivial and trivial phases, are usually gapless, or commonly referred as metallic states. For example, the surface state of a topological insulator is a gapless Dirac state. These metallic topological boundary states are typically well described by non-interacting fermions. However, the behavior of topological boundary states with significant electron–electron interactions, which could turn the gapless boundary states into gapped ordered states, e.g., density wave states or superconducting states, is of great interest theoretically, but is still lacking evidence experimentally. Here, we report the observation of incommensurable charge density wave(CDW) formed on the topological boundary states driven by the electron–electron interactions on the(0 0 1) surface of Co Si. The wavevector of CDW varies as the temperature changes, which coincides with the evolution of topological surface Fermi arcs with temperature. The orientation of the CDW phase is determined by the chirality of the Fermi arcs, which indicates a direct association between CDW and Fermi arcs. Our finding will stimulate the search of more interactions-driven ordered states, such as superconductivity and magnetism, on the boundaries of topological materials.
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