Fluctuating spin stripes in the normal state of high-Tc cuprate superconductors

Recent experiments have established charge stripes as universal in underdoped cuprate superconductors. In contrast, spin stripes, which are intimately tied to charge stripes in many doped Mott insulators, are seemingly absent in the majority of cuprates, at least in the static long-ranged form. Whether spin stripes exist in a subtle fluctuating form in these cuprates is controversial, with proponents suggesting a link between fluctuating stripes and the mechanism of high-$T_c$ superconductivity. Here, we use numerically exact determinant quantum Monte Carlo calculations to demonstrate dynamical spin stripe correlations in the three-band Hubbard model, which represents the local electronic structure of a Cu-O plane in a cuprate superconductor. Unlike existing ground state studies, our simulations are conducted at temperatures approaching the pseudogap regime, indicated by a decrease in the Knight shift upon cooling, and hence reflect properties of the normal, non-superconducting state. Calculations of the dynamic spin susceptibility strongly support the interpretation of a variety of experimental observations in terms of the physics of fluctuating stripes, including the ubiquitous hourglass magnetic dispersion and the Yamada plot of incommensurability vs. doping.