Correlated Quantum Chains with a Finite Concentration of Impurities

P. Schlottmann

Andrei A. Zvyagin

Quantum Spin- Chain with the Nearest-Neighbour Couplings Co-Ordinate Bethe Ansatz for a Heisenberg-Ising Ring Correlated Electron Chains: Co-Ordinate Bethe Ansatz Algebraic Bethe Ansatz Correlated Quantum Chains with Open Boundary Conditions Correlated Quantum Chains with Isolated Impurities Correlated Quantum Chains with a Finite Concentration of Impurities Finite Size Corrections in Quantum Correlated Chains Beyond the Integrability: Approximate Methods.

Youichirou Iino, Masatoshi Imada

Effects of nonmagnetic impurity doping on an AF spin-1/2 Heisenberg ladder system are studied by the QMC method. A single nonmagnetic impurity induces a localized spin-1/2 moment accompanied by "static" and enhanced AF correlations around it. Small and finite concentration of impurities induces a remarkable change of magnetic and thermodynamic properties with gapless excitations. It also shows rather sharp but continuous crossover around the concentration of about 4%. Above the crossover concentration, all the spins are strongly coupled participating in the enhanced and rather uniform power-law decay of the antiferromagnetic correlation. Below the crossover, each impurity forms an antiferromagnetic cluster only weakly coupled each other. For random distribution of impurities, large Curie-like susceptibility accompanied with small residual entropy is obtained at low temperatures in agreement with recent experimental observation in Zn-doped $SrCu_{2}O_{3}$. Temperature dependence of AF susceptibility shows power-law-like but weaker divergence than the single chain AFH in the temperature range studied.

M. Fannes, Bruno Nachtergaele, Reinhard F. Werner

Olga V. Man’ko