Scaling of entanglement entropy for chains of arbitrary spin

Abstract

We investigate the entanglement entropy of a 1D Hamiltonian written in terms of the generalized Gell-Mann matrices that shares some properties with the spin-1/2 XXZ model. In particular, we study the point that marks the boundary between a critical phase and a ferromagnetic phase. This point cannot be described by a conformal field theory and its ground state is infinitely degenerate in the thermodynamic limit. We find an analytical expression for the ground state and its Schmidt decomposition, and show that the entanglement entropy scales as s log2 L in the leading order, where L is the size of the subsystem and s is the spin. The scaling is related to the symmetric-like structure of the ground state.