Spin defects in spin-Peierls systems

We examine spin-Peierls states in the presence of spin defects for CuGeO3 where magnetic ions Cu2+ replaced by non-magnetic ones Zn2+. Based on the action for the bosonized Hamiltonian, the state is investigated by using path integral method. The temperature of spin-Peierls transition T-SP and, the spin gap and the magnitude of the averaged lattice dimerization in the ground state have been calculated as a function of doping. From comparison of the present TSP with the experimental result, a good agreement is obtained for the transition temperature of Cu-1-deltaZndeltaGeO3 in the region of the doping rate, delta < 0.02.