Based on symmetry analysis and lattice model calculations,we demonstrate that Dirac nodal line(DNL)can stably exist in two-dimensional(2D)nonmagnetic as well as antiferromagnetic systems.We focus on the situations whe...Based on symmetry analysis and lattice model calculations,we demonstrate that Dirac nodal line(DNL)can stably exist in two-dimensional(2D)nonmagnetic as well as antiferromagnetic systems.We focus on the situations where the DNLs are enforced by certain symmetries and the degeneracies on the DNLs are inevitable even if spin–orbit coupling is strong.After thorough analysis,we find that five space groups,namely 51,54,55,57 and 127,can enforce the DNLs in 2D nonmagnetic semimetals,and four type-III magnetic space groups(51.293,54.341,55.355,57.380)plus eight type-IV magnetic space groups(51.299,51.300,51.302,54.348,55.360,55.361,57.387 and 127.396)can enforce the DNLs in 2D antiferromagnetic semimetals.By breaking these symmetries,the different 2D topological phases can be obtained.Furthermore,by the first-principles electronic structure calculations,we predict that monolayer YB4C4 is a good material platform for studying the exotic properties of 2D symmetry-enforced Dirac node-line semimetals.展开更多
Node line semimetals(NLSMs) were characterized by one-dimensional band crossings in their bulk electronic structures.The nontrivial band topology of NLSM gives rise to "drumhead" surface electronic excitatio...Node line semimetals(NLSMs) were characterized by one-dimensional band crossings in their bulk electronic structures.The nontrivial band topology of NLSM gives rise to "drumhead" surface electronic excitations that exhibits exotic physical properties.The symmetries of crystalline provide the needed protection of node line from being gapped out by the perturbations that preserve the symmetry.The progress of NLSM in tungsten-based materials is reviewed with an emphasis on their symmetry-based protection,characteristic electronic band structures and their response to the spin-orbit coupling(SOC)and breaking of time-reversal symmetry.The potential exploration directions of tungsten-based NLSM in the future are also discussed.展开更多
基金supported by the National Natural Science Foundation of China(No.12204533)K Liu was supported by the National Key R&D Program of China(Grant No.2017YFA0302903)+2 种基金the Fundamental Research Funds for the Central Universities(CN),and the Research Funds of Renmin University of China(Grant No.19XNLG13)Z X Liu was supported by the National Natural Science Foundation of China(Grant Nos.12134020 and 11974421)Z Y Lu was supported by the National Natural Science Foundation of China(Grant No.11934020).
文摘Based on symmetry analysis and lattice model calculations,we demonstrate that Dirac nodal line(DNL)can stably exist in two-dimensional(2D)nonmagnetic as well as antiferromagnetic systems.We focus on the situations where the DNLs are enforced by certain symmetries and the degeneracies on the DNLs are inevitable even if spin–orbit coupling is strong.After thorough analysis,we find that five space groups,namely 51,54,55,57 and 127,can enforce the DNLs in 2D nonmagnetic semimetals,and four type-III magnetic space groups(51.293,54.341,55.355,57.380)plus eight type-IV magnetic space groups(51.299,51.300,51.302,54.348,55.360,55.361,57.387 and 127.396)can enforce the DNLs in 2D antiferromagnetic semimetals.By breaking these symmetries,the different 2D topological phases can be obtained.Furthermore,by the first-principles electronic structure calculations,we predict that monolayer YB4C4 is a good material platform for studying the exotic properties of 2D symmetry-enforced Dirac node-line semimetals.
基金supported by the National Natural Foundation of China (NFSC)(Grants No.11574215)。
文摘Node line semimetals(NLSMs) were characterized by one-dimensional band crossings in their bulk electronic structures.The nontrivial band topology of NLSM gives rise to "drumhead" surface electronic excitations that exhibits exotic physical properties.The symmetries of crystalline provide the needed protection of node line from being gapped out by the perturbations that preserve the symmetry.The progress of NLSM in tungsten-based materials is reviewed with an emphasis on their symmetry-based protection,characteristic electronic band structures and their response to the spin-orbit coupling(SOC)and breaking of time-reversal symmetry.The potential exploration directions of tungsten-based NLSM in the future are also discussed.
