Quantum Monte Carlo Studies on Attractive Hubbard Model with Anisotropic Spin-dependent Hopping on Two-leg Ladder Lattice

Using spin-dependent hopping, it is possible to have a fully paired state with a gap for single fermion excitation and gapless Cooper pair excitation, called `Cooper-pair Bose-metal' phase. Recently, the existence of this phase was suggested by a density matrix renormalization group studies\footnote{ Feiguin, A.E. and M.P.A. Fisher, \textit{Exotic paired phases in ladders with spin-dependent hopping.} Physical Review B, 2011. \textbf{83}(11): p. 115104.} on the attractive Hubbard Model with two-leg ladder geometry and anisotropic spin-dependent hopping. We here present a detailed Quantum Monte Carlo (QMC) studies on this model to investigate its finite temperature properties, including correlation function, s-wave and d-wave pairing function, and finally to deduce the existence and behavior of `Cooper-pair Bose-metal' phase.