Angle-dependent magnetoresistance measurements in Tl2Ba2CuO6+δ and the need for anisotropic scattering

The angle-dependent interlayer magnetoresistance of overdoped Tl2Ba2CuO6+delta has been measured in high magnetic fields up to 45 T. A conventional Boltzmann transport analysis with no basal-plane anisotropy in the cyclotron frequency omega(c) or transport lifetime tau is shown to be inadequate for explaining the data. We describe in detail how the analysis can be modified to incorporate in-plane anisotropy in these two key quantities and extract the degree of anisotropy for each by assuming a simple fourfold symmetry. While anisotropy in omega(c) and other Fermi surface parameters may improve the fit, we demonstrate that the most important anisotropy is that in the transport lifetime, thus confirming its role in the physics of overdoped superconducting cuprates.