Multiflavor Mott insulators in quantum materials and ultracold atoms

Fuente: arXiv
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Main Authors: Chen, Gang V., Wu, Congjun
Format: Preprint
Published: 2021
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author Chen, Gang V.
Wu, Congjun
author_facet Chen, Gang V.
Wu, Congjun
contents Mott insulators with large and active (or multiflavor) local Hilbert spaces widely occur in quantum materials and ultracold atomic systems, and are dubbed "multiflavor Mott insulators". For these multiflavored Mott insulating materials, the spin-only description with the quadratic spin interactions is often insufficient to capture the major physical processes. In the situation with active orbitals, the Kugel-Khomskii superexchange model was then proposed. We briefly review this historical model and discuss the modern developments beyond the original spin-orbital context. These include and are not restricted to the $4d$/$5d$ transition metal compounds with the spin-orbit-entangled $J=3/2$ quadruplets, the rare-earth magnets with two weakly-separated crystal field doublets, breathing magnets and/or the cluster and molecular magnets, et al. We explain the microscopic origin of the emergent Kugel-Khomskii physics in each realization with some emphasis on the $J=3/2$ quadruplets, and refer the candidate multiflavor Mott insulators as "$J=3/2$ Mott insulators". For the ultracold atoms, we review the multiflavor Mott insulator realization with the ultracold alkaline and alkaline-earth atoms on the optical lattices. Despite a large local Hilbert space from the atomic hyperfine spin states, the system could naturally realize a large symmetry group such as the Sp($N$) and SU($N$) symmetries. These ultracold atomic systems lie in the large-$N$ regime of these symmetry groups and are characterized by strong quantum fluctuations. The Kugel-Khomskii physics and the exotic quantum ground states with the "baryon-like" physics can appear in various limits. We conclude with our vision and outlook on this subject.
format Preprint
id arxiv_https___arxiv_org_abs_2112_02630
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Multiflavor Mott insulators in quantum materials and ultracold atoms
Chen, Gang V.
Wu, Congjun
Strongly Correlated Electrons
Materials Science
Quantum Gases
Mott insulators with large and active (or multiflavor) local Hilbert spaces widely occur in quantum materials and ultracold atomic systems, and are dubbed "multiflavor Mott insulators". For these multiflavored Mott insulating materials, the spin-only description with the quadratic spin interactions is often insufficient to capture the major physical processes. In the situation with active orbitals, the Kugel-Khomskii superexchange model was then proposed. We briefly review this historical model and discuss the modern developments beyond the original spin-orbital context. These include and are not restricted to the $4d$/$5d$ transition metal compounds with the spin-orbit-entangled $J=3/2$ quadruplets, the rare-earth magnets with two weakly-separated crystal field doublets, breathing magnets and/or the cluster and molecular magnets, et al. We explain the microscopic origin of the emergent Kugel-Khomskii physics in each realization with some emphasis on the $J=3/2$ quadruplets, and refer the candidate multiflavor Mott insulators as "$J=3/2$ Mott insulators". For the ultracold atoms, we review the multiflavor Mott insulator realization with the ultracold alkaline and alkaline-earth atoms on the optical lattices. Despite a large local Hilbert space from the atomic hyperfine spin states, the system could naturally realize a large symmetry group such as the Sp($N$) and SU($N$) symmetries. These ultracold atomic systems lie in the large-$N$ regime of these symmetry groups and are characterized by strong quantum fluctuations. The Kugel-Khomskii physics and the exotic quantum ground states with the "baryon-like" physics can appear in various limits. We conclude with our vision and outlook on this subject.
title Multiflavor Mott insulators in quantum materials and ultracold atoms
topic Strongly Correlated Electrons
Materials Science
Quantum Gases
url https://arxiv.org/abs/2112.02630