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Accueil du site > Publications > Publications 2008 > Thermodynamics of impurities in the anisotropic Heisenberg spin-1/2 chain

Thermodynamics of impurities in the anisotropic Heisenberg spin-1/2 chain

J. Sirker, S. Fujimoto, N. Laflorencie, S. Eggert, and I. Affleck

par Nicolas Laflorencie - 9 janvier 2008

The thermodynamics of finite open antiferromagnetic XXZ chains is studied using field theory, Bethe Ansatz and quantum Monte Carlo methods. For the susceptibility a parameter-free result as a function of the number of sites L and temperature T beyond the scaling limit is derived. The limiting cases T/J >> 1/L (J being the exchange constant), where the boundary correction shows a logarithmically suppressed Curie behaviour, and T/J << 1/L, where a crossover to the ground state behaviour takes place, are discussed in detail. Based on this analysis we present a simple formula for the averaged susceptibility of a spin-1/2 chain doped with non-magnetic impurities. We show that the effective Curie constant has a highly non-trivial temperature dependence and shows scaling in the low-temperature limit. Finally, corrections due to intra- and interchain couplings and implications for experiments on Sr_2 Cu_1-xPd_x O_3+\delta and related compounds are discussed.