Topological materials have attracted extensive attention in con-densed 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 discov-ered in several three-dimensional(3D)bulk materials[6-8].Flour-ishing 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 correspond-ing symmetry operations and groups are significantly reduced,nar-rowing the range of candidate structures.In some 2D materials,the non-symmorphic symmetry[9]is shown to protect the fourfold degeneracy of DPs at certain isolated k points against SOC[10-12],but no SOC resistant fourfold DNL state was even predicted in real materials so far.

Deping Guo;Pengjie Guo;Shijing Tan;Min Feng;Limin Cao;Zheng-Xin Liu;Kai Liu;Zhong-Yi Lu;Wei Ji

Beijing Key Laboratory of Optoelectronic Functional Materials&Micro-Nano Devices,Department of Physics,Renmin University of China,Beijing 100872,China;Songshan Lake Materials Laboratory,Dongguan 523808,China;Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China;Hefei National Laboratory for Physical Sciences at the Microscale,University of Science and Technology of China,Hefei 230026,China;School of Physics and Technology and Key Laboratory of Artificial Micro-and Nano-Structures of Ministry of Education,Wuhan University,Wuhan 430072,China;Institute for Advanced Studies,Wuhan University,Wuhan 430072,China

科学通报（英文版）

[1]Deping Guo;Pengjie Guo;Shijing Tan;Min Feng;Limin Cao;Zheng-Xin Liu;Kai Liu;Zhong-Yi Lu;Wei Ji-.Two-dimensional Dirac-line semimetals resistant to strong spin-orbit coupling)[J].科学通报（英文版）,2022(19):1954-1957

DNLSMs,ishing,rowing,symmorphic

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