Effect of anisotropic impurity scattering in superconductors

TL;DR

This paper investigates how anisotropic impurity scattering affects the critical temperature in superconductors, highlighting the importance of scattering potential symmetry and matching experimental data for cuprates.

Contribution

It introduces a detailed analysis of anisotropic impurity effects within the weak-coupling BCS framework, considering different scattering limits and symmetries.

Findings

Impurity potential symmetry significantly influences pair-breaking.

Theoretical results align with experimental data for Zn doping and oxygen irradiation.

Impurity effects vary between d-wave and (d+s)-wave superconductors.

Abstract

We discuss the weak-coupling BCS theory of a superconductor with the impurities, accounting for their anisotropic momentum-dependent potential. The impurity scattering process is considered in the t-matrix approximation and its influence on the superconducting critical temperature is studied in the Born and unitary limit for a d- and (d+s)-wave superconductors. We observe a significant dependence of the pair-breaking strength on the symmetry of the scattering potential and classify the impurity potentials according to their ability to alter T_c. A good agreement with the experimental data for Zn doping and oxygen irradiation in the overdoped cuprates is found.