Abstract
Some nonequilibrium properties of an impurity in a linear chain of spins with nearest-neighbor interaction of the isotropic XY type are studied. It is shown that under certain conditions its behavior is in agreement with the general principles of statistical mechanics. The relaxation in the presence of a transverse field is also studied, and it is found that in the weak coupling region the approach to equilibrium is described by a sum of exponentials. However, the results do not agree with the solution of the Bloch equations.