We theoretically study the charge order and orbital magnetic properties of a new type of antiferromagnetic kagome metal FeGe.Based on first-principles density functional theory calculations,we study the electronic str...We theoretically study the charge order and orbital magnetic properties of a new type of antiferromagnetic kagome metal FeGe.Based on first-principles density functional theory calculations,we study the electronic structures,Fermi-surface quantum fluctuations,as well as phonon properties of the antiferromagnetic kagome metal FeGe.It is found that charge density wave emerges in such a system due to a subtle cooperation between electron-electron interactions and electron–phonon couplings,which gives rise to an unusual scenario of interaction-triggered phonon instabilities,and eventually yields a charge density wave(CDW)state.We further show that,in the CDW phase,the ground-state current density distribution exhibits an intriguing star-of-David pattern,leading to flux density modulation.The orbital fluxes(or current loops)in this system emerge as a result of the subtle interplay between magnetism,lattice geometries,charge order,and spin-orbit coupling(SOC),which can be described by a simple,yet universal,tight-binding theory including a Kane-Mele-type SOC term and a magnetic exchange interaction.We further study the origin of the peculiar step-edge states in FeGe,which sheds light on the topological properties and correlation effects in this new type of kagome antiferromagnetic material.展开更多
Here we review scanning tunneling microscopy research on the surface determination for various types of kagome materials,including 11-type(CoSn,FeSn,FeGe),32-type(Fe_(3)Sn_(2)),13-type(Mn_(3)Sn),135-type(AV_(3)Sb_(5),...Here we review scanning tunneling microscopy research on the surface determination for various types of kagome materials,including 11-type(CoSn,FeSn,FeGe),32-type(Fe_(3)Sn_(2)),13-type(Mn_(3)Sn),135-type(AV_(3)Sb_(5),A=K,Rb,Cs),166-type(TbMn6Sn_(6),YMn_(6)Sn_(6)and ScV_(6)Sn_(6)),and 322-type(Co_(3)Sn_(2)S_(2)and Ni_(3)In_(2)Se_(2)).We first demonstrate that the measured step height between different surfaces typically deviates from the expected value of±0.4∼0.8Å,which is owing to the tunneling convolution effect with electronic states and becomes a serious issue for Co_(3)Sn_(2)S_(2)where the expected Sn-S interlayer distance is 0.6Å.Hence,we put forward a general methodology for surface determination as atomic step geometry imaging,which is fundamental but also experimentally challenging to locate the step and to image with atomic precision.We discuss how this method can be used to resolve the surface termination puzzle in Co_(3)Sn_(2)S_(2).This method provides a natural explanation for the existence of adatoms and vacancies,and beyond using unknown impurity states,we propose and use designer layer-selective substitutional chemical markers to confirm the validity of this method.Finally,we apply this method to determine the surface of a new kagome material Ni_(3)In_(2)Se_(2),as a cousin of Co_(3)Sn_(2)S_(2),and we image the underlying kagome geometry on the determined Se surface above the kagome layer,which directly visualizes the p-d hybridization physics.We emphasize that this general method does not rely on theory,but the determined surface identity can provide guidelines for first-principles calculations with adjustable parameters on the surface-dependent local density of states and quasi-particle interference patterns.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.12174257)the National Key R&D program of China(Grant No.2020YFA0309601)+1 种基金the Science and Technology Commission of the Shanghai Municipality(Grant No.21JC1405100)the Start-Up Grant of ShanghaiTech University。
文摘We theoretically study the charge order and orbital magnetic properties of a new type of antiferromagnetic kagome metal FeGe.Based on first-principles density functional theory calculations,we study the electronic structures,Fermi-surface quantum fluctuations,as well as phonon properties of the antiferromagnetic kagome metal FeGe.It is found that charge density wave emerges in such a system due to a subtle cooperation between electron-electron interactions and electron–phonon couplings,which gives rise to an unusual scenario of interaction-triggered phonon instabilities,and eventually yields a charge density wave(CDW)state.We further show that,in the CDW phase,the ground-state current density distribution exhibits an intriguing star-of-David pattern,leading to flux density modulation.The orbital fluxes(or current loops)in this system emerge as a result of the subtle interplay between magnetism,lattice geometries,charge order,and spin-orbit coupling(SOC),which can be described by a simple,yet universal,tight-binding theory including a Kane-Mele-type SOC term and a magnetic exchange interaction.We further study the origin of the peculiar step-edge states in FeGe,which sheds light on the topological properties and correlation effects in this new type of kagome antiferromagnetic material.
基金supported by the National Natural Science Foundation of China(11734003,62275016,12274029,and 92163206)the National Key Research and Development Program of China(2020YFA0308800)+1 种基金Beijing Natural Science Foundation(Z210006 and Z190006)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB30000000)。
基金support from the National Key R&D Program of China(No.2023YFA1407300)the National Science Foundation of China(No.12374060)+1 种基金Project funded by China Postdoctoral Science Foundation(No.2023M741546,No.2023M731530)The work at Princeton is supported by Gordon and Betty Moore Foundation(GBMF4547 and GBMF9461,M.Z.H.).
文摘Here we review scanning tunneling microscopy research on the surface determination for various types of kagome materials,including 11-type(CoSn,FeSn,FeGe),32-type(Fe_(3)Sn_(2)),13-type(Mn_(3)Sn),135-type(AV_(3)Sb_(5),A=K,Rb,Cs),166-type(TbMn6Sn_(6),YMn_(6)Sn_(6)and ScV_(6)Sn_(6)),and 322-type(Co_(3)Sn_(2)S_(2)and Ni_(3)In_(2)Se_(2)).We first demonstrate that the measured step height between different surfaces typically deviates from the expected value of±0.4∼0.8Å,which is owing to the tunneling convolution effect with electronic states and becomes a serious issue for Co_(3)Sn_(2)S_(2)where the expected Sn-S interlayer distance is 0.6Å.Hence,we put forward a general methodology for surface determination as atomic step geometry imaging,which is fundamental but also experimentally challenging to locate the step and to image with atomic precision.We discuss how this method can be used to resolve the surface termination puzzle in Co_(3)Sn_(2)S_(2).This method provides a natural explanation for the existence of adatoms and vacancies,and beyond using unknown impurity states,we propose and use designer layer-selective substitutional chemical markers to confirm the validity of this method.Finally,we apply this method to determine the surface of a new kagome material Ni_(3)In_(2)Se_(2),as a cousin of Co_(3)Sn_(2)S_(2),and we image the underlying kagome geometry on the determined Se surface above the kagome layer,which directly visualizes the p-d hybridization physics.We emphasize that this general method does not rely on theory,but the determined surface identity can provide guidelines for first-principles calculations with adjustable parameters on the surface-dependent local density of states and quasi-particle interference patterns.
