Susceptibilities of Sr(Cu_(1-x)Zn_x)₂O₃ Studied by Quantum Monte Carlo Simulation

The effects of non-magnetic impurities randomly doped into a two-leg Heisenberg spin ladder are investigated. Using the continuous time quantum Monte Carlo loop algorithm we calculate the uniform and staggered susceptibilities of such a system. The obtained uniform susceptibility is well described in terms of an effective model of weakly interacting local moments induced by non-magnetic impurities for a 1% doping case, but not for higher concentrations. The staggered susceptibility however is significantly enhanced over that in the effective model already at 1% doping. Using a mean field approximation for the interladder coupling, we explain qualitatively the phase diagram of Sr(Cu_{1-x}Zn_x)_2O_3.