Manifestation of spin-charge separation in the dynamic dielectric response of one--dimensional Sr2CuO3

TL;DR

This study experimentally demonstrates spin-charge separation in a one-dimensional insulator, Sr2CuO3, through its dynamic dielectric response, aligning with theoretical predictions of the Hubbard model.

Contribution

First experimental observation of spin-charge separation in Sr2CuO3 using electron energy-loss spectroscopy, confirming theoretical models for one-dimensional correlated insulators.

Findings

Observation of momentum-dependent low-energy features

Detection of an exciton-like peak at higher momentum transfer

Agreement with extended Hubbard model predictions

Abstract

We have determined the dynamical dielectric response of a one-dimensional, correlated insulator by carrying out electron energy-loss spectroscopy on Sr2CuO3 single crystals. The observed momentum and energy dependence of the low-energy features, which correspond to collective transitions across the gap, are well described by an extended one-band Hubbard model with moderate nearest neighbor Coulomb interaction strength. An exciton-like peak appears with increasing momentum transfer. These observations provide experimental evidence for spin-charge separation in the relevant excitations of this compound, as theoretically expected for the one-dimensional Hubbard model.