Entanglement entropy in the Lipkin-Meshkov-Glick model
  We analyze the entanglement entropy in the Lipkin-Meshkov-Glick model, which describes mutually interacting spins half embedded in a magnetic field. This entropy displays a singularity at the critical point that we study as a function of the interaction anisotropy, the magnetic field, and the system size. Results emerging from our analysis are surprisingly similar to those found for the one-dimensional XY chain. 
J. I. Latorre, R. Orus, E. Rico, J. Vidal