Temperature dependent scattering rates at the Fermi surface of optimally doped Bi2Sr2CaCu2O8+δ

For optimally doped Bi2Sr2CaCu2O8+delta, scattering rates in the normal state are found to have a linear temperature dependence over most of the Fermi surface. In the immediate vicinity of the (pi, 0) point, thr scattering rates are nearly constant in the normal state, consistent with models in which scattering at this point determines the c-axis transport. In the superconducting stale, the scattering rates away from the nodal direction appear to level off and become temperature independent.