Exotic paired phases in ladders with spin-dependent hopping

Abstract

Fermions in two-dimensions (2D) when subject to anisotropic spin-dependent hopping can potentially give rise to unusual paired states in {\it unpolarized} mixtures that can behave as non-Fermi liquids. One possibility is a fully paired state with a gap for fermion excitations in which the Cooper pairs remain uncondensed. Such a "Cooper-pair Bose-metal" phase would be expected to have a singular Bose-surface in momentum space. As demonstrated in the context of 2D bosons hopping with a frustrating ring-exchange interaction, an analogous Bose-metal phase has a set of quasi-1D descendent states when put on a ladder geometry. Here we present a density matrix renormalization group (DMRG) study of the attractive Hubbard model with spin-dependent hopping on a two-leg ladder geometry. In our setup, one spin species moves preferentially along the leg direction, while the other does so along the rung direction. We find compelling evidence for the existence of a novel Cooper-pair Bose-metal phase in a region of the phase diagram at intermediate coupling. We further explore the phase diagram of this model as a function of hopping anisotropy, density, and interaction strength, finding a conventional superfluid phase, as well as a phase of paired Cooper pairs with d-wave symmetry, similar to the one found in models of hard-core bosons with ring-exchange. We argue that simulating this model with cold Fermi gases on spin dependent optical lattices is a promising direction for realizing exotic quantum states.

10 pages, 12 figures

References in corpus (24)

• Quantum phase transition from a superfluid to a Mott insulator in a gas of ultracold atoms
• The density-matrix renormalization group
• Synthetic magnetic fields for ultracold neutral atoms
• Controlled Collisions for Multiparticle Entanglement of Optically Trapped Atoms
• Coherent transport of neutral atoms in spin-dependent optical lattice potentials
• Interior Gap Superfluidity
• New Trends in Density Matrix Renormalization
• Two-Dimensional Superconducting Fluctuations in Stripe-Ordered La(1.875)Ba(0.125)CuO(4)
• BEC-BCS crossover in "magnetized" Feshbach-resonantly paired superfluids
• Striped superconductors: How the cuprates intertwine spin, charge and superconducting orders
• Degenerate Fermi Gases of Ytterbium
• Charge $4e$ superconductivity from pair density wave order in certain high temperature superconductors
• The Crystallography of Color Superconductivity
• BEC-BCS crossover, phase transitions and phase separation in polarized resonantly-paired superfluids
• Atomic quantum simulator for lattice gauge theories and ring exchange models
• Stability Criteria for Breached Pair Superfluidity
• Quantum liquid crystals in imbalanced Fermi gas: fluctuations and fractional vortices in Larkin-Ovchinnikov states
• Theory of the striped superconductor
• Spin Bose-Metal phase in a spin-1/2 model with ring exchange on a two-leg triangular strip
• D-wave correlated Critical Bose Liquids in two dimensions
• Spin-Dependent Hubbard Model and a Quantum Phase Transition in Cold Atoms
• Strong-Coupling Phases of Frustrated Bosons on a 2-leg Ladder with Ring Exchange
• Pair correlations of a spin-imbalanced Fermi gas on two-leg ladders
• Exotic paired states with anisotropic spin-dependent Fermi surfaces

Cited by in corpus (8)

• Studying Two Dimensional Systems With the Density Matrix Renormalization Group
• Bose Metals and Insulators on Multi-Leg Ladders with Ring Exchange
• p-wave Superfluidity by Spin-Nematic Fermi Surface Deformation
• Density Matrix Recursion Method: Genuine Multisite Entanglement Distinguishes Odd from Even Quantum Heisenberg Ladders
• Ising phase transitions and thermodynamics of correlated fermions in a two-dimensional spin-dependent lattice potential
• Two-leg fermionic Hubbard ladder system in the presence of state-dependent hopping
• Mott insulator phases of non-locally coupled bosons in bilayer optical superlattices
• Ising Antiferromagnet in the 2D Hubbard Model with Mismatched Fermi Surfaces