From conformal to volume-law for the entanglement entropy in   exponentially deformed critical spin 1/2 chains
  An exponential deformation of 1D critical Hamiltonians gives rise to ground states whose entanglement entropy satisfies a volume-law. This effect is exemplified in the XX and Heisenberg models. In the XX case we characterize the crossover between the critical and the maximally entangled ground state in terms of the entanglement entropy and the entanglement spectrum. 
Giovanni Ram\'irez, Javier Rodr\'iguez-Laguna, Germ\'an Sierra
cond-mat.str-el cond-mat.stat-mech quant-ph