Intrinsic Impurity in the High Temperature Superconductor Bi_2Sr_2CaCu_2O$_{8+δ}$
arXiv:0707.3171
Abstract
The {}^{17}O NMR spectra of Bi_2Sr_2CaCu_2O$_{8+δ}$ (Bi-2212) single crystals were measured in the temperature range from 4 K to 200 K and magnetic fields from 3 to 29 T, reported here principally at 8 T. The NMR linewidth of the oxygen in the CuO_{2} plane was found to be magnetically broadened with the temperature dependence of a Curie law where the Curie coefficient decreases with increased doping. This inhomogeneous magnetism is an impurity effect intrinsic to oxygen doping and persists unmodified into the superconducting state.
10 pages, 5 figures