The Influence of $s$-$d$ Exchange Interaction on the Gap Anisotropy and Anisotropy of the Lifetime of Normal State Charge Carriers of Layered Cuprates

TL;DR

This paper investigates how $s$-$d$ exchange interactions influence the anisotropy of electron scattering rates and lifetimes in layered cuprates, linking normal state properties with superconducting gap features using a unified Hamiltonian approach.

Contribution

It demonstrates that the same $s$-$d$ exchange Hamiltonian can describe both the normal and superconducting states of cuprates, providing a unified theoretical framework.

Findings

Correlation between hot/cold spots and superconducting gap regions.

Qualitative agreement of $2\Delta_{max}/T_c$ with Pokrovsky theory.

Derived the $s$-$d$ interaction kernel in the LCAO approximation.

Abstract

The anisotropy of the electron scattering rate and lifetime $\Gamma_\mathbf{p}=1/\tau_\mathbf{p}$ observed by Angle Resolved Photoemission Spectroscopy (ARPES) is evaluated using $s$-$d$ Kondo-Zener exchange Hamiltonian used previously to describe superconducting properties of high-$T_c$ cuprates; for correlation between critical temperature $T_c$ and BCS coupling constant, for example. The performed qualitative analysis reveals that "cold spots" correspond to nodal regions of the superconducting phase where the superconducting gap is zero, because the exchange interaction is annulled. Vice versa, "hot spots" and intensive scattering in the normal state correspond to the regions with maximal gap in the superconducting phase. We have obtained that separable kernel postulated in the Fermi liquid approach to the normal phase is the same kernel which is exactly calculated in the framework of the $s$-$d$ approach in the Linear Combination of Atomic Orbital (LCAO) approximation for CuO$_2$ plane. In this sense, at least on the qualitative level, the superconducting cuprates are described by one and the same Hamiltonian applied to their superconducting and normal properties. For the overdopedcuprates having conventional Fermi liquid behavior we derived the corresponding Stoss-integral for the $s$-$d$ interaction in the framework of LCAO approximation which is the central result of the present study. Repeating the thermodynamics we observed that for optimally doped cuprates $2\Delta_\mathrm{max}/T_c$ is in good agreement with Pokrovsky theory for anisotropic gap superconductors.