Spectral function and dynamical spin correlation function in the image–image–image–image model Original Research Article

Using exact spectral functions of the tt–t′t′–t″t″–JJ model obtained by the exact diagonalization technique, we construct the dynamical spin response function. In the hole-doped system, the spin correlation shows a sand-glass-like behavior qualitatively similar to those observed in neutron scattering experiments. This is only clearly seen in the presence of t′t′ and t″t″, implying the importance of the Fermi-arc for the sand-glass behavior. On the other hand, the spin correlation function in the electron-doped system does not display the sand-glass-like behavior but shows a behavior similar to a spin-wave-like excitation observed in experiments.