The electronic evolution of Mott insulators into exotic correlated phases remains puzzling,because of electron interaction and inhomogeneity.Introduction of individual imperfections in Mott insulators could help captu...The electronic evolution of Mott insulators into exotic correlated phases remains puzzling,because of electron interaction and inhomogeneity.Introduction of individual imperfections in Mott insulators could help capture the main mechanism and serve as a basis to understand the evolution.Here we utilize scanning tunneling microscopy to probe the atomic scale electronic structure of the spin-orbit-coupling assisted Mott insulator Sr_(3)Ir_(2)O_(7).It is found that the tunneling spectra exhibit a homogeneous Mott gap in defect-free regions,but near the oxygen vacancy in the rotated Ir O_(2)plane the local Mott gap size is significantly enhanced.We attribute the enhanced gap to the locally reduced hopping integral between the 5d electrons of neighboring Ir sites via the bridging planar oxygen p orbitals.Such bridging defects have a dramatic influence on local bandwidth,thus provide a new way to manipulate the strength of Mottness in a Mott insulator.展开更多
The magnetic and electronic properties of spinel oxide LiV2O4 have been systematically studied by using the spin-polarized first-principles electronic structure calculations.We find that a series of magnetic states,in...The magnetic and electronic properties of spinel oxide LiV2O4 have been systematically studied by using the spin-polarized first-principles electronic structure calculations.We find that a series of magnetic states,in which the ferromagnetic(FM)V4 tetrahedra are linked together through the corner-sharing antiferromagnetic(AFM)V4 tetrahedra,possess degenerate energies lower than those of other spin configurations.The large number of these energetically degenerated states being the magnetic ground state give rise to strong magnetic frustration as well as large magnetic entropy in LiV2O4.The corresponding band structure and density of states of such a typical magnetic state in this series,i.e.,the ditetrahedron(DT)AFM state,demonstrate that LiV2O4 is in the vicinity of a metal-insulator transition.Further analysis suggests that the t2g and eg orbitals of the V atoms play different roles in the magnetic exchange interactions.Our calculations are consistent with previous experimental measurements and shed light on understanding the exotic magnetism and the heavy-fermion behavior of LiV2O4.展开更多
基金the National Key R&D Program of China(Grant No.2017YFA0302900)the Basic Science Center Project of National Natural Science Foundation of China(Grant No.51788104)+4 种基金supported in part by the Beijing Advanced Innovation Center for Future Chip(ICFC)Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physicssupported by the National Natural Science Foundation of China(Grant No.12074424)the Fundamental Research Funds for the Central Universitiesthe Research Funds of Renmin University of China。
文摘The electronic evolution of Mott insulators into exotic correlated phases remains puzzling,because of electron interaction and inhomogeneity.Introduction of individual imperfections in Mott insulators could help capture the main mechanism and serve as a basis to understand the evolution.Here we utilize scanning tunneling microscopy to probe the atomic scale electronic structure of the spin-orbit-coupling assisted Mott insulator Sr_(3)Ir_(2)O_(7).It is found that the tunneling spectra exhibit a homogeneous Mott gap in defect-free regions,but near the oxygen vacancy in the rotated Ir O_(2)plane the local Mott gap size is significantly enhanced.We attribute the enhanced gap to the locally reduced hopping integral between the 5d electrons of neighboring Ir sites via the bridging planar oxygen p orbitals.Such bridging defects have a dramatic influence on local bandwidth,thus provide a new way to manipulate the strength of Mottness in a Mott insulator.
基金Project supported by the National Key R&D Program of China(Grant Nos.2017YFA0302903 and 2019YFA0308603)the National Natural Science Foundation of China(Grant Nos.11774422,11774424,and 11674374)+1 种基金the CAS Interdisciplinary Innovation Team,the Fundamental Research Funds for the Central Universities,Chinathe Research Funds of Renmin University of China(Grant No.19XNLG13).
文摘The magnetic and electronic properties of spinel oxide LiV2O4 have been systematically studied by using the spin-polarized first-principles electronic structure calculations.We find that a series of magnetic states,in which the ferromagnetic(FM)V4 tetrahedra are linked together through the corner-sharing antiferromagnetic(AFM)V4 tetrahedra,possess degenerate energies lower than those of other spin configurations.The large number of these energetically degenerated states being the magnetic ground state give rise to strong magnetic frustration as well as large magnetic entropy in LiV2O4.The corresponding band structure and density of states of such a typical magnetic state in this series,i.e.,the ditetrahedron(DT)AFM state,demonstrate that LiV2O4 is in the vicinity of a metal-insulator transition.Further analysis suggests that the t2g and eg orbitals of the V atoms play different roles in the magnetic exchange interactions.Our calculations are consistent with previous experimental measurements and shed light on understanding the exotic magnetism and the heavy-fermion behavior of LiV2O4.
