LOW-TEMPERATURE PROPERTIES OF THE RANDOMLY DEPLETED HEISENBERG LADDER

Low-temperature thermodynamic properties of the spin-1/2 Heisenberg la dder system with non-magnetic impurities are discussed using an effect ive Hamiltonian for the impurity-induced spins in the background of a spin liquid with a gap. It is shown that the uniform susceptibility sh ows Curie-like behavior in high-, intermediate-, and low-temperature r egimes, with three different Curie constants. The ratio of specific he at to temperature, C/T, is divergent in the low-temperature limit, ref lecting a singular distribution of the effective couplings among the i mpurity spins.