Theory of the Resistive Transition in Overdoped $Tl_2Ba_2CuO_{6+x}$: Implications for the angular dependence of the quasiparticle scattering rate in High-$T_c$ superconductors

TL;DR

This paper investigates the resistive transition in overdoped Tl2Ba2CuO6+x, revealing inhomogeneity and a highly anisotropic quasiparticle scattering rate, with implications for understanding vortex dynamics in high-Tc superconductors.

Contribution

It introduces a microscopic model linking quasiparticle lifetime anisotropy to vortex viscosity and inhomogeneity in overdoped cuprates, supported by experimental data analysis.

Findings

Vortex viscosity is anomalously small near the superconducting transition.

The material exhibits microscopic inhomogeneity with regions of higher local T_c.

Quasiparticle lifetime varies dramatically around the Fermi surface, being longest along the zone diagonal.

Abstract

We show that recent measurements of the magnetic field dependence of the magnetization, specific heat and resistivity of overdoped $T_c \sim 17K$ $Tl_{2}Ba_{2}CuO_{6+\delta}$ in the vicinity of the superconducting $H_{c2}$ imply that the vortex viscosity is anomalously small and that the material studied is inhomogeneous with small, a few hundred $\AA$, regions in which the local $T_{c}$ is much higher than the bulk $T_{c}$. The anomalously small vortex viscosity can be derived from a microscopic model in which the quasiparticle lifetime varies dramatically around the Fermi surface, being small everywhere except along the zone diagonal (``cold spot''). We propose experimental tests of our results.