Angle dependent magnetoresistance measurements in Tl$_2$Ba$_2$CuO$_{6+\delta}$ and the need for anisotropic scattering

TL;DR

This study measures the angle-dependent magnetoresistance in overdoped Tl$_2$Ba$_2$CuO$_{6+eta}$ and highlights the necessity of considering anisotropic scattering, especially in the transport lifetime, to accurately interpret the data.

Contribution

It introduces a modified Boltzmann transport analysis that incorporates in-plane anisotropy in cyclotron frequency and transport lifetime, emphasizing the dominant role of anisotropic scattering in cuprates.

Findings

Anisotropy in transport lifetime is crucial for explaining magnetoresistance data.

Conventional isotropic models are inadequate for overdoped cuprates.

In-plane anisotropy significantly improves the fit to experimental data.

Abstract

The angle-dependent interlayer magnetoresistance of overdoped Tl$_2$Ba$_2$CuO$_{6+\delta}$ has been measured in high magnetic fields up to 45 Tesla. 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 four-fold 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.