Mobius molecules and fragile Mott insulators

Article

关键词: HUBBARD-MODEL;    RING CURRENTS;    TRANSITION;    LATTICE;    CHAINS;    RULES;   

DOI  :  10.1103/PhysRevB.90.245142

来源: SCIE

【 摘 要 】

Motivated by the concept of Mobius 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.

【 授权许可】

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