Stability of (N+1) -body fermion clusters in a multiband Hubbard model
| Autor: | M. Iskin, A. Keleş |
|---|---|
| Přispěvatelé: | Işkın, Menderes (ORCID 0000-0003-0704-1318 & YÖK ID 29659), Keleş, A., College of Sciences, Department of Physics |
| Jazyk: | angličtina |
| Rok vydání: | 2022 |
| Předmět: |
Condensed Matter::Quantum Gases
Condensed Matter - Strongly Correlated Electrons Cold atoms and matter waves Cold gases in optical lattices Fermi gases Strongly correlated systems Hubbard model Strongly Correlated Electrons (cond-mat.str-el) Quantum Gases (cond-mat.quant-gas) FOS: Physical sciences Condensed Matter::Strongly Correlated Electrons Condensed Matter - Quantum Gases Optics Physics |
| Zdroj: | Physical Review A |
| Popis: | We start with a variational approach and derive a set of coupled integral equations for the bound states of $N$ identical spin-$\uparrow$ fermions and a single spin-$\downarrow$ fermion in a generic multiband Hubbard Hamiltonian with an attractive onsite interaction. As an illustration we apply our integral equations to the one-dimensional sawtooth lattice up to $N \le 3$, i.e., to the $(3+1)$-body problem, and reveal not only the presence of tetramer states in this two-band model but also their quasi-flat dispersion when formed in a flat band. Furthermore, for $N = \{4, 5, \cdots, 10 \}$, our DMRG simulations and exact diagonalization suggest the presence of larger and larger multimers with lower and lower binding energies, conceivably without an upper bound on $N$. These peculiar $(N+1)$-body clusters are in sharp contrast with the exact results on the single-band linear-chain model where none of the $N \ge 2$ multimers appear. Hence their presence must be taken into account for a proper description of the many-body phenomena in flat-band systems, e.g., they may suppress superconductivity especially when there exists a large spin imbalance. 15 pages with 7 figures; to appear in PRA |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|