Difference of optical conductivity between one- and two-dimensional doped nickelates

TL;DR

This paper investigates the differences in optical conductivity between one- and two-dimensional doped nickelates, attributing the variations to dimensionality-dependent hopping integrals, and successfully explains experimental observations.

Contribution

It provides a theoretical explanation for the spectral differences in doped nickelates based on dimensionality effects on hopping integrals, aligning with experimental data.

Findings

Significant spectral differences in the gap region between 1D and 2D nickelates.

Hopping integral dependence on dimensionality explains the spectral variations.

Theoretical results are consistent with experimental data in Y$_{2-x}$Ca$_x$BaNiO$_5$ and La$_{2-x}$Sr$_x$NiO$_4$.

Abstract

We study the optical conductivity in doped nickelates, and find the dramatic difference of the spectrum in the gap ($\omega$$\alt$4 eV) between one- (1D) and two-dimensional (2D) nickelates. The difference is shown to be caused by the dependence of hopping integral on dimensionality. The theoretical results explain consistently the experimental data in 1D and 2D nickelates, Y$_{2-x}$Ca$_x$BaNiO$_5$ and La$_{2-x}$Sr$_x$NiO$_4$, respectively. The relation between the spectrum in the X-ray aborption experiments and the optical conductivity in La$_{2-x}$Sr$_x$NiO$_4$ is discussed.