Tuning the entanglement for a one-dimensional magnetic system with anisotropic coupling and impurities

We study a set of localized spins coupled through exchange interaction and subject to an external magnetic field. We demonstrate, for such a class of one-dimensional magnetic systems, that entanglement can be controlled and tuned by varying the anisotropy parameter in the Hamiltonian and by introducing impurities into the systems. In particular, for certain parameters, the entanglement is zero up to a critical point λc, where a quantum phase transition occurs, and is different from zero above λc.