The complex symmetry breaking states in AV3Sb5 family have attracted extreme research attention,but controversy still exists,especially in the question of time reversal symmetry breaking of the charge density wave(CDW...The complex symmetry breaking states in AV3Sb5 family have attracted extreme research attention,but controversy still exists,especially in the question of time reversal symmetry breaking of the charge density wave(CDW).Most recently,a chiral CDW has been suggested in kagome magnet FeGe,but the related study is very rare.Here,we use a scanning tunneling microscope to study the symmetry breaking behavior of both the short-and long-range CDWs in FeGe.Different from previous studies,our study reveals an isotropic long-range CDW without obvious symmetry breaking,while local rotational symmetry breaking appears in the short-range CDW,which may be related to the existence of strong structural disorders.Moreover,the charge distribution of the short-range CDW is inert to the applied external magnetic fields and the detailed spin arrangements of FeGe,inconsistent with the expectation of a chiral CDW associated with chiral flux.Our results rule out the existence of spontaneous chiral and rotational symmetry breaking in the CDW state of FeGe,putting strong constraints on the further understanding of CDW mechanism.展开更多
The structure, transport, and magnetic properties of LaxBi0.5.xSr0.5MnO3 （LBSMO） （x=0.1 and 0.4） were studied through X-ray diffraction, magnetization, and electron spin resonance （ESR） measurements. The structu...The structure, transport, and magnetic properties of LaxBi0.5.xSr0.5MnO3 （LBSMO） （x=0.1 and 0.4） were studied through X-ray diffraction, magnetization, and electron spin resonance （ESR） measurements. The structural analysis showed that the LBSMO crystallized in an orthorhombic perovskite structure with Pbnm space group for x=-0.1 and Imma space group for x=0.4 and the highly polarizable 6s^2 lone pair of Bi^3＋ was the ttming factor for the structural variations. Magnetic studies revealed that the replacement of Bi ions by La ions resulted in the collapse high temperature charge ordering state of BSMO and it order Ferro Magnetically （FM） with Tc around 355 and 330 K for x=0.1 and 0.4, respectively. Both ESR, temperature and field dependant magnetization suggested that there was a coexistence of FM and the paramagnetic phases well below Tc and the FM and CO-AFM phases below 250 K of LBSMO.展开更多
The kagome metal FeGe provides a rich platform for understanding the mechanisms behind competing orders,as it exhibits charge order(CO)emerging deep within the antiferromagnetic phase.To investigate the intrinsic orig...The kagome metal FeGe provides a rich platform for understanding the mechanisms behind competing orders,as it exhibits charge order(CO)emerging deep within the antiferromagnetic phase.To investigate the intrinsic origin of this behavior,we examine the evolution of the low-energy electronic structure across the phase transition in annealed FeGe samples using angleresolved photoemission spectroscopy.We find no evidence supporting a conventional nesting mechanism,such as Fermi surface nesting or van Hove singularities.However,we observe two notable changes in the band structure:an electron-like band around the K point and another around the A point,both shifting upward in energy when CO forms.These findings are consistent with our density-functional theory calculations,which suggest that the charge order in FeGe is primarily driven by magnetic energy savings due to a lattice distortion involving Ge1-dimerization.Our results provide photoemission evidence supporting this novel mechanism for CO formation in FeGe,in contrast to the conventional nesting-driven mechanisms.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12374140,12494593,11790312,12004056,11774060,and 92065201)the National Key R&D Program of China(Grant No.2023YFA1406304)+2 种基金the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302803)the Fundamental Research Funds for the Central Universities of China(Grant Nos.2022CDJXY-002 and WK9990000103)the New Cornerstone Science Foundation.
文摘The complex symmetry breaking states in AV3Sb5 family have attracted extreme research attention,but controversy still exists,especially in the question of time reversal symmetry breaking of the charge density wave(CDW).Most recently,a chiral CDW has been suggested in kagome magnet FeGe,but the related study is very rare.Here,we use a scanning tunneling microscope to study the symmetry breaking behavior of both the short-and long-range CDWs in FeGe.Different from previous studies,our study reveals an isotropic long-range CDW without obvious symmetry breaking,while local rotational symmetry breaking appears in the short-range CDW,which may be related to the existence of strong structural disorders.Moreover,the charge distribution of the short-range CDW is inert to the applied external magnetic fields and the detailed spin arrangements of FeGe,inconsistent with the expectation of a chiral CDW associated with chiral flux.Our results rule out the existence of spontaneous chiral and rotational symmetry breaking in the CDW state of FeGe,putting strong constraints on the further understanding of CDW mechanism.
基金the Ministry of Hunan Resources and Development (India)
文摘The structure, transport, and magnetic properties of LaxBi0.5.xSr0.5MnO3 （LBSMO） （x=0.1 and 0.4） were studied through X-ray diffraction, magnetization, and electron spin resonance （ESR） measurements. The structural analysis showed that the LBSMO crystallized in an orthorhombic perovskite structure with Pbnm space group for x=-0.1 and Imma space group for x=0.4 and the highly polarizable 6s^2 lone pair of Bi^3＋ was the ttming factor for the structural variations. Magnetic studies revealed that the replacement of Bi ions by La ions resulted in the collapse high temperature charge ordering state of BSMO and it order Ferro Magnetically （FM） with Tc around 355 and 330 K for x=0.1 and 0.4, respectively. Both ESR, temperature and field dependant magnetization suggested that there was a coexistence of FM and the paramagnetic phases well below Tc and the FM and CO-AFM phases below 250 K of LBSMO.
基金supported by the National Natural Science Foundation of China(Grant Nos.12174362,11888101,11790312,92065202,12474142,and 12174365)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302803)the New Cornerstone Science Foundation.Part of this research used Beamline 03U of the Shanghai Synchrotron Radiation Facility,which is supported by the ME2 project from the National Natural Science Foundation of China(Grant No.11227902).
文摘The kagome metal FeGe provides a rich platform for understanding the mechanisms behind competing orders,as it exhibits charge order(CO)emerging deep within the antiferromagnetic phase.To investigate the intrinsic origin of this behavior,we examine the evolution of the low-energy electronic structure across the phase transition in annealed FeGe samples using angleresolved photoemission spectroscopy.We find no evidence supporting a conventional nesting mechanism,such as Fermi surface nesting or van Hove singularities.However,we observe two notable changes in the band structure:an electron-like band around the K point and another around the A point,both shifting upward in energy when CO forms.These findings are consistent with our density-functional theory calculations,which suggest that the charge order in FeGe is primarily driven by magnetic energy savings due to a lattice distortion involving Ge1-dimerization.Our results provide photoemission evidence supporting this novel mechanism for CO formation in FeGe,in contrast to the conventional nesting-driven mechanisms.
