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Möbius molecules and fragile Mott insulators

Author(s): Muechler, Lukas; Maciejko, Joseph; Neupert, Titus; Car, Roberto

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Abstract: Motivated by the concept of Möbius aromatics in organic chemistry, we extend the recently introduced concept of fragile Mott insulators (FMI) to ring-shaped molecules with repulsive Hubbard interactions threaded by a half-quantum of magnetic flux (hc/2e). In this context, an FMI is the insulating ground state of a finite-size molecule that cannot be adiabatically connected to a single Slater determinant, i.e., to a band insulator, provided that time-reversal and lattice translation symmetries are preserved. Based on exact numerical diagonalization for finite Hubbard interaction strength U and existing Bethe-ansatz studies of the one-dimensional Hubbard model in the large-U limit, we establish a duality between Hubbard molecules with 4n and 4n + 2 sites, with n integer. A molecule with 4n sites is an FMI in the absence of flux but becomes a band insulator in the presence of a half-quantum of flux, while a molecule with 4n + 2 sites is a band insulator in the absence of flux but becomes an FMI in the presence of a half-quantum of flux. Including next-nearest-neighbor hoppings gives rise to new FMI states that belong to multidimensional irreducible representations of the molecular point group, giving rise to a rich phase diagram.
Publication Date: 15-Dec-2014
Electronic Publication Date: 23-Dec-2014
Citation: Muechler, Lukas, Maciejko, Joseph, Neupert, Titus, Car, Roberto. (2014). Möbius molecules and fragile Mott insulators. Physical Review B, 90 (24), 10.1103/PhysRevB.90.245142
DOI: doi:10.1103/PhysRevB.90.245142
ISSN: 1098-0121
EISSN: 1550-235X
Pages: 245142-1 - 245142-7
Type of Material: Journal Article
Journal/Proceeding Title: Physical Review B
Version: Final published version. Article is made available in OAR by the publisher's permission or policy.

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