Emergent orbitals in the cluster Mott insulator on a breathing kagome lattice
Name
PhysRevB.97.035124.pdf
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1.52 MB
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Adobe PDF
Checksum (MD5)
ebb0285a8693d7826d12d8ae33764bb1
Author(s)
Chen, Gang
Lee, Patrick A
Date Issued
January 2018
Journal
Physical Review B
Publisher
American Physical Society
Citation
Chen, Gang, and Patrick A. Lee. “Emergent Orbitals in the Cluster Mott Insulator on a Breathing Kagome Lattice.” Physical Review B, vol. 97, no. 3, Jan. 2018. © 2018 American Physical Society
Version
Final published version
Abstract
Motivated by the recent developments on cluster Mott insulating materials such as the cluster magnet LiZn[subscript 2]Mo[subscript 3]O[subscript 8], we consider the strong plaquette charge ordered regime of the extended Hubbard model on a breathing kagome lattice and reveal the properties of the cluster Mottness. The plaquette charge order arises from the intersite charge interaction and the collective motion of three localized electrons on the hexagon plaquettes. This model leads naturally to a reduction of the local moments by 2/3, as observed in LiZn[subscript 2]Mo[subscript 3]O[subscript 8]. Furthermore, at low temperatures, each hexagon plaquette contains an extra orbital-like degree of freedom in addition to the remaining spin 1/2. We explore the consequence of this emergent orbital degree of freedom. We point out the interaction between the local moments is naturally described by a Kugel-Khomskii spin-orbital model. We develop a parton approach and suggest a spin-liquid ground state with spinon Fermi surfaces for this model. We further predict an emergent orbital order when the system is under a strong magnetic field. Various experimental consequences for LiZn[subscript 2]Mo[subscript 3]O[subscript 8] are discussed, including an argument that the charge ordering must be short ranged if the charge per Mo is slightly off stoichiometric.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1103/PhysRevB.97.035124
