INTERPLAY OF HOLON AND SPINON DYNAMICS IN DOPED ANISOTROPIC HEISENBERG-CHAINS

The role played by doping in one-dimensional quantum antiferromagnets is investigated using a decoupling of the charge and spin degrees of f reedom that allows for magnetic phase changes when the concentration o f holes increases. Our approach predicts quasi-continuous as well as d iscontinuous metal-insulator transitions, depending on the nature of t he corresponding magnetic transformation. We also provide a clue for t he observed behavior of the Hall coefficient, with a sign change cause d by doping, suggesting that the change in the character of carriers i s related to different magnetic correlations.