Magnetic Susceptibility of an integrable anisotropic spin ladder system

摘要

We investigate the thermodynamics of a spin ladder model which possesses afree parameter besides the rung and leg couplings. The model is exactly solvedby the Bethe Ansatz and exhibits a phase transition between a gapped and agapless spin excitation spectrum. The magnetic susceptibility is obtainednumerically and its dependence on the anisotropy parameter is determined. Aconnection with the compounds KCuCl3, Cu2(C5H12N2)2Cl4 and (C5H12N)2CuBr4 inthe strong coupling regime is made and our results for the magneticsusceptibility fit the experimental data remarkably well.