Oxygen phonon branches in overdoped La$_{1.7}$Sr$_{0.3}$CuO$_4$

TL;DR

This study investigates how doping affects oxygen phonon modes in overdoped La$_{1.7}$Sr$_{0.3}$CuO$_4$, revealing larger renormalization but smaller linewidths compared to optimally doped samples, with no charge stripe features.

Contribution

It provides detailed measurements of phonon dispersion and linewidths in overdoped La$_{1.7}$Sr$_{0.3}$CuO$_4$, highlighting differences from optimally doped compounds.

Findings

Larger doping-induced phonon renormalization in overdoped sample

Smaller phonon linewidths in overdoped La$_{1.7}$Sr$_{0.3}$CuO$_4$

Absence of charge stripe features in overdoped sample

Abstract

The dispersion of the Cu-O bond-stretching vibrations in overdoped La$_{1.7}$Sr$_{0.3}$CuO$_4$ (not superconducting) has been studied by high resolution inelastic neutron scattering. It was found that the doping-induced renormalization of the so-called breathing and the half-breathing modes is larger than in optimally doped La$_{1.85}$Sr$_{0.15}$CuO$_4$. On the other hand, the phonon linewidths are generally smaller in the overdoped sample. Features observed in optimally doped La$_{1.85}$Sr$_{0.15}$CuO$_4$ which suggest a tendency towards charge stripe formation are absent in overdoped La$_{1.7}$Sr$_{0.3}$CuO$_4$.