Evolution of a polaron band through the phase diagram of Nd[2-x]Ce[x]CuO[4-y]

TL;DR

This study tracks how polaronic absorption features evolve with doping and temperature in high-Tc superconductors, revealing their persistence in superconducting phases and disappearance in overdoped metallic states, thus informing polaron theories.

Contribution

It provides comprehensive experimental data on polaron behavior across the entire phase diagram of Nd[2-x]Ce[x]CuO[4-y], highlighting the evolution of polaron bands with doping and temperature.

Findings

Polaron band softens with increased doping.

Polaron band persists in the superconducting phase.

Polaron band vanishes in the overdoped metallic phase.

Abstract

The evolution with doping and temperature of the polaronic absorption in a family of high-T$_c$ superconductors is first followed here across the whole phase diagram. The polaron band softens with increasing doping, is still present in the superconducting phase, and vanishes in the overdoped metallic phase. These results point toward the existence of polaron aggregates at low temperature and may provide an experimental ground for the increasing number of theoretical descriptions of many-polaron systems.