Raman Scattering versus Infrared Conductivity: Evidence for one-dimensional Conduction in La_{2-x}Sr_{x}CuO_{4}

TL;DR

This study compares Raman and infrared spectra of underdoped La_{1.90}Sr_{0.10}CuO_{4} to investigate low-energy electronic excitations, revealing evidence for one-dimensional conduction along Cu-O bonds at low temperatures.

Contribution

It provides experimental evidence for one-dimensional conduction in La_{2-x}Sr_{x}CuO_{4} using combined Raman and IR spectroscopy, highlighting unconventional low-energy spectral features.

Findings

IR conductivity shows finite-frequency peaks absent in Raman spectra

Spectral weight shifts to lower energies below 100 K

A long-lived electronic component develops along Cu-O bonds

Abstract

Raman and Infrared (IR) spectra of an underdoped La_{1.90}Sr_{0.10}CuO_{4} single crystal have been measured as a function of temperature. Both techniques provide unconventional low-energy spectra. The IR conductivity exhibits features peaked at finite frequencies which do not have a counterpart in the Raman response. Below approximately 100 K a transfer of both Raman and IR spectral weight towards lower energies is found and a new component in the Raman response builds up being characterized by a very long lifetime of electrons propagating along the Cu-O bonds.