Effect of mediated interactions on a Hubbard chain in mixed-dimensional fermionic cold atoms

Abstract

Cold atom experiments can now realize mixtures where different components move in different spatial dimensions. We investigate a fermion mixture where one species is constrained to move along a one-dimensional lattice embedded in a two-dimensional lattice populated by another species of fermions, and where all bare interactions are contact interactions. By focusing on the one-dimensional fermions, we map this problem onto a model of fermions with nonlocal interactions on a chain. The effective interaction is mediated by the two-dimensional fermions and is both attractive and retarded, the form of which can be varied by changing the density of the two-dimensional fermions. By using the functional renormalization group in the weak-coupling limit and ignoring the retardation effect, we show that the one-dimensional fermions can be controlled to be in various density-wave, or spin-singlet or spin-triplet superconducting phases.