Dynamical probes of the elementary excitation spectrum for 2D spin models

Abstract Using the 2D Jordan–Wigner fermionization we calculate the zz dynamic structure factor of the s= 1 2 isotropic XY model on a spatially anisotropic square lattice. Within the frames of our approach S zz ( k ,ω) is governed by a two-fermion excitation continuum. We discuss the modes ω k at which most of the spectral weight is concentrated or which form the boundaries of the continuum. We illustrate our findings considering in some detail the spatially isotropic case.