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.
Original language | English (US) |
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Article number | 245142 |
Journal | Physical Review B - Condensed Matter and Materials Physics |
Volume | 90 |
Issue number | 24 |
DOIs | |
State | Published - Dec 23 2014 |
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics