Spin-spectral-weight distribution and energy range of the parent compound La$_2$CuO$_4$

TL;DR

This study analyzes the spin spectral weight distribution in La$_2$CuO$_4$ using the Hubbard model, revealing higher-energy features up to 566 meV and confirming the appropriate U/t ratio, with implications for understanding spin wave damping.

Contribution

The paper provides a detailed theoretical analysis of the spectral-weight distribution in La$_2$CuO$_4$ within the Hubbard model, extending the energy range beyond previous experiments and clarifying the U/t parameter range.

Findings

Higher-energy spectral weight extends to about 566 meV.

Spectral weight at $[ ext{pi}, ext{pi}]$ is significant near the higher energy.

Intensity at $[ ext{pi},0]$ is negligible, consistent with damped spin waves.

Abstract

The spectral-weight distribution in recent neutron scattering experiments on the parent compound La$_2$CuO$_4$ (LCO), which are limited in energy range to about 450\,meV, is studied in the framework of the Hubbard model on the square lattice. We find that the higher-energy weight extends to about 566\,meV and is located at and near the momentum $[\pi,\pi]$. Our results confirm that the $U/t$ value suitable to LCO is in the range $U/t\in (6,8)$. The continuum weight energy-integrated intensity vanishes or is extremely small at momentum $[\pi,0]$. This behavior of the intensity is consistent with that of spin waves, which are damped at $[\pi,0]$.