Superconductivity and charge order of confined Fermi systems

Abstract

The low-temperature properties of the two-dimensional attractive Hubbard model are strongly influenced by the fermion density. Away from half-filling, there is a finite-temperature transition to a phase with s-wave pairing order. However, the critical temperature is suppressed to zero at half-filling, where long-range charge-density-wave order also appears, degenerate with superconductivity. This paper presents Determinant Quantum Monte Carlo simulations of the attractive Hubbard model in the presence of a confining potential V which makes the fermion density ρ inhomogeneous across the lattice. Pair correlations are shown to be large at low temperatures in regions of the trapped system with incommensurate filling, and to exhibit a minimum as the local density ρ(i) passes through one fermion per site. In this ring of ρ=1, charge order is enhanced. A comparison is made between treating V within the local-density approximation (LDA) and in an ab initio manner. It is argued that certain sharp features of the LDA result at integer filling do not survive the proximity of doped sites. The critical temperature of confined systems of fixed characteristic density is estimated.

7 pages, 5 figures; minor changes from v1

References in corpus (10)

• Evidence for Superfluidity of Ultracold Fermions in an Optical Lattice
• Molecules of Fermionic Atoms in an Optical Lattice
• Local quantum criticality in confined fermions on optical lattices
• Quantum Simulation of the Hubbard Model: The Attractive Route
• Strongly renormalized quasi-two-dimensional electron gas in a heterostructure with correlation effects
• s-wave Superconductivity Phase Diagram in the Inhomogeneous Two-Dimensional Attractive Hubbard Model
• Pure Mott phases in confined ultracold atomic systems
• Disordered two-dimensional superconductors: roles of temperature and interaction strength
• Variational Monte Carlo analysis of the Hubbard model with a confining potential: one-dimensional fermionic optical lattice systems
• Quasi-long-range order in trapped systems

Cited by in corpus (5)

• Quantum gas microscopy of an attractive Fermi-Hubbard system
• Inhomogeneous BCS-BEC crossover for trapped cold atoms in optical lattices
• The Pairing of Spin-orbit Coupled Fermi Gas in Optical Lattice
• Simulation of inhomogeneous distributions of ultracold atoms in an optical lattice via a massively parallel implementation of nonequilibrium strong-coupling perturbation theory
• Radio frequency spectroscopy of the attractive Hubbard model in a trap