Over the decade,Dirac semimetals(DSMs)have been exten-sively studied[1].However,the hallmarks of DSMs are still not clear[2,3].Recently,a generalized bulk-boundary correspondence,namely higher-order bulk-hinge correspondence,for DSMs[4-7]has been proposed,i.e.,one-dimensional(1D)higher-order Fermi arcs(HOFAs)are direct and topological consequences of 3D bulk Dirac points.The 3D bulk Dirac points lead to the nontrivial filling anomaly η[8,9]of the 2D insulating momentum-space plane away from them,which ensures the presence of gapless mid-gap states on 1D hinges.When the 2D plane passes through the bulk Dirac point,the filling anomaly changes from nontrivial to trivial.At last,the gapless mid-gap states form the HOFAs,which connect the hinge projections of the 3D bulk Dirac points.The change of the filling anomaly △ηis a topological invariant(i.e.,either a Z2 or a Z3 depending on the rotational symmetry),and can be used to characterize the 3D bulk Dirac points[5].Although Ref.[4]pro-posed some candidates hosting HOFAs,these materials exhibit sur-face Fermi arcs.Therefore,it is still challenging and highly desirable to find a realistic DSM without surface Fermi arcs but with HOFAs.

Simin Nie;Jia Chen;Changming Yue;Congcong Le;Danwen Yuan;Zhijun Wang;Wei Zhang;Hongming Weng

Department of Materials Science and Engineering,Stanford University,Stanford CA 94305,USA;Zhejiang Lab,Hangzhou 311121,China;Department of Physics,University of Fribourg,Fribourg 1700,Switzerland;RIKEN Interdisciplinary Theoretical and Mathematical Sciences(iTHEMS),Wako,Saitama 351-0198,Japan;Fujian Provincial Key Laboratory of Quantum Manipulation and New Energy Materials,College of Physics and Energy,Fujian Normal University,Fuzhou 350117,China;Fujian Provincial Collaborative Innovation Center for Advanced High-field Superconducting Materials and Engineering,Fuzhou 350117,China;Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China;School of Physics,University of Chinese Academy of Sciences,Beijing 100049,China;Songshan Lake Materials Laboratory,Dongguan 523808,China

科学通报（英文版）

[1]Simin Nie;Jia Chen;Changming Yue;Congcong Le;Danwen Yuan;Zhijun Wang;Wei Zhang;Hongming Weng-.Tunable Dirac semimetals with higher-order Fermi arcs in Kagome lattices Pd3Pb2X2(X=S,Se))[J].科学通报（英文版）,2022(19):1958-1961

Pd3Pb2X2,HOFAs

Tunable,Dirac,semimetals,higher,order,Fermi,arcs,Kagome,lattices,Se,Over,decade,DSMs,have,been,exten,sively,studied,However,hallmarks,are,still,not,clear,Recently,generalized,bulk,boundary,correspondence,namely,has,proposed,one,dimensional,1D,direct,topological,consequences,points,lead,nontrivial,filling,anomaly,2D,insulating,momentum,space,plane,away,from,them,which,ensures,presence,gapless,mid,states,hinges,When,passes,through,changes,At,last,form,connect,projections,invariant,either,Z2,Z3,depending,rotational,symmetry,used,characterize,Although,Ref,some,candidates,hosting,these,materials,exhibit,Therefore,challenging,highly,desirable,find,realistic,without,surface,but

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