Stripes, pair density wave, and holon Wigner crystal in single-band Hubbard model on diagonal square lattice

Abstract: We investigate the ground-state properties of the Hubbard model on wide diagonal square cylinders, rotated by $\pi/4$ relative to the regular lattice orientation. Using state-of-the-art density matrix renormalization group calculations with a large number of states, we convincingly demonstrate the development of a unidirectional charge density wave (CDW) characterized by infinite-length stripes along the primitive vector of square lattice in models with next-nearest-neighbor hopping $t'=-0.1\sim -0.3$ and doping $\delta \sim 14\%$. Intriguingly, analysis of pair-pair correlation functions along these stripes reveals incommensurate pair density wave (PDW) superconductivity with diverged susceptibility. To the best of our knowledge, this is probably the first controlled numerical evidence of dominant PDW in the single-band Hubbard model on square lattices. At lower doping $\delta \sim 10\%$, we observed the formation of an additional CDW order within each stripe, which aligns across different stripes, forming a holon Wigner crystal phase. The spin pattern retains antiferromagnetic stripes with anti-phase domain walls. The ordering momentum of this emerged CDW order is remarkably close to the center-of-mass momentum of Cooper pairs in the PDW phase, suggesting a multifaceted relationship between CDW and PDW ordering.