On The Application of Antiferromagnetic Fermi Liquid Theory on NMR Experiments in La1.85 Sr0.15 CuO4

H. Monien, P. Monthous, and D. Pines

90-016

NMR experiments on La$_{1.85}$Sr$_{0.15}$CuO$_4$ by Kitaoka et al. and Imai et al. are analyzed using the phenomenological antiferromagnetic Fermi theory of Millis, Monein, and Pines, and the results are compared with those previously obtaINED FOR YBa$_2$Cu$_2$O$_7$ AND YBa$_2$Cu$_3$O$_{6.63}$. A one-component model, with hyperfine couplings which are unchanged from those found previously for YBa$_2$Cu$_2$O$_7$ AND YBa$_2$Cu$_3$O$_{6.63}$, and parameters obtained from experiment, provides a quantitative fit to the data. At all temperatures the antiferromagnetic correlations found in La$_{1.85}$Sr$_{0.15}$CuO$_4$ are stronger than those found for the YBCO samples with the result that the characteristic energy for the antiferromagnetic paramagnons which describe the AF spin dynamics is quite low ($< kT$ and ~20K at $T_c$). We use the deduced paramagnon energies to calculate the contribution to the electrical resistivity from quasiparticle-antiferromagnetic paramagnon scattering for La$_{1.85}$Sr$_{0.15}$CuO$_4$, YBa$_2$ Cu$_3$O$_7$, and YBa$_2$Cu$_3$O$_{6.63}$, and find that it displays a linear temperature dependence for all three materials. Our results support the proposal that the properties of a nearly antiferromagnetic Fermi liquid are genuinely novel, and suggest that both the spin and charge aspects of the normal state properties of the cuprate oxide superconductors can be quantitatively explained in terms of quasiparticles coupled to antiferromagnetic paramagnons whose charateristic energy scale is $< kT$.