MONTE-CARLO STUDY OF THE NMR PROPERTIES OF THE QUASI-2D HEISENBERG-ANTIFERROMAGNET DOPED WITH REAL-SPACE PAIRS

A Monte Carlo study of a model of real space pairs (RSP's), moving in a quasi-2D Heisenberg antiferromagnet, is presented. It is found that, in a system without (Coulomb) repulsion between the RSP's, the system of RSP's may phase-separate or remain homogeneous, depending on the RSP density and on the ratio of the antiferromagnetic (AF) coupling parameter J to the RSP bandwidth. In the first case, the RSP's become static, whereas in the second case the RSP's remain dynamic. The effects of the doping on the antiferromagnetic correlation length are presented, together with the NMR Knight shift K and spin lattice relaxation time (1/(T1T)), and the specific heat. It turns out that the interaction of dynamic holes with the AF system suppresses the growth of the AF correlation length substantially. Finally, a comparison with recent analytical work on the same model, and with experimental results on high-T(c) superconductors, is presented. It turns out that the model describes the experimentally observed behavior of 1/(T1T) and K quite well.