Anisotropic microwave conductivity of cuprate superconductors in the presence of CuO chain induced impurities

TL;DR

This study models the anisotropic microwave conductivity in ortho-II YBa₂Cu₃O₆.₅, highlighting the role of CuO chain impurities in causing directional differences in superconducting properties.

Contribution

It introduces a theoretical framework considering CuO chain impurities to explain microwave conductivity anisotropy in cuprate superconductors.

Findings

Impurity scattering from CuO chains explains anisotropic conductivity.

The model reproduces experimental energy and temperature dependence.

CuO chain impurities are identified as the main source of anisotropy.

Abstract

The anisotropy in the microwave conductivity of the ortho-II YBa$_2$Cu$_3$O$_{6.50}$ is studied within the kinetic energy driven superconducting mechanism. The ortho-II YBa$_2$Cu$_3$O$_{6.50}$ is characterized by a periodic alternative of filled and empty $\hat{b}$-axis CuO chains. By considering the CuO chain induced extended anisotropy impurity scattering, the main features of the anisotropy in the microwave conductivity of the ortho-II YBa$_2$Cu$_3$O$_{6.50}$ are reproduced based on the nodal approximation of the quasiparticle excitations and scattering processes, including the intensity and lineshape of the energy and temperature dependence of the $\hat{a}$-axis and $\hat{b}$-axis microwave conductivities. Our results also confirm that the $\hat{b}$-axis CuO chain induced impurity is the main source of the anisotropy.