  The thermal entanglement of a two-qubit anisotropic Heisenberg $XYZ$ chain
under an inhomogeneous magnetic field b is studied. It is shown that when
inhomogeneity is increased to certain value, the entanglement can exhibit a
larger revival than that of less values of b. The property is both true for
zero temperature and a finite temperature. The results also show that the
entanglement and critical temperature can be increased by increasing
inhomogeneous exteral magnetic field.
