Relaxation in the neighborhood of a magnetic impurity in the s=1/2 Heisenberg chain at high temperatures

A Mori-Lee theoretic study of spin relaxation in the neighborhood of a magnetic impurity in the s=1/2 nearest-neighbor (NN) Heisenberg chain at high temperatures is presented. Our calculations suggest that in the limit of zero impurity coupling, the spectral function for the ''surface spin'' is consistent with a set of discrete frequencies given approximately by wn[n(w0+1/4)-1/4] against a shallow continuum background, where w03J/4 with 2J being the coupling between NN spins. The frequencies broaden as the impurity coupling is increased to the NN coupling.