Electrodynamics of the Nodal Metal in Weakly Doped High-$T_{c}$ Cuprates

TL;DR

This study provides a detailed analysis of the infrared conductivity in high-$T_c$ cuprates, revealing the electromagnetic response of the nodal metal state characterized by a two-component conductivity, and re-evaluates the role of magnetic excitations in these materials.

Contribution

It offers a comprehensive dataset on the IR response of the nodal metal in cuprates and critically reassesses the interpretation of optical data, especially regarding magnetic excitations.

Findings

Identification of a two-component conductivity in the nodal metal

Evidence of Fermi liquid behavior in the IR response

Re-evaluation of magnetic excitations' role in self energy effects

Abstract

We report on the detailed analysis of the infrared (IR) conductivity of two prototypical high-$T_{c}$ systems YBa$_{2}$Cu$_{3}$O$_{y}$ and La$_{2-x}$Sr$%_{x}$CuO$_{4}$ throughout the complex phase diagram of these compounds. Our focus in this work is to thoroughly document the electromagnetic response of the nodal metal state which is initiated with only few holes doped in parent antiferromagnetic systems and extends up to the pseudogap boundary in the phase diagram. The key signature of the nodal metal is the two-component conductivity: the Drude mode at low energies followed by a resonance in mid-IR. The Drude component can be attributed to the response of coherent quasiparticles residing on the Fermi arcs detected in photoemission experiments. The microscopic origin of the mid-IR band is yet to be understood. A combination of transport and IR data uncovers fingerprints of the Fermi liquid behavior in the response of the nodal metal. The comprehensive nature of the data sets presented in this work allows us to critically re-evaluate common approaches to the interpretation of the optical data. Specifically we re-examine the role of magnetic excitations in generating electronic self energy effects through the analysis of the IR data in high magnetic field.