Magnetic excitations in L-edge resonant inelastic x-ray scattering from one-dimensional cuprates

TL;DR

This paper investigates magnetic excitations in one-dimensional cuprates using L-edge RIXS, revealing contributions from both on-site and neighboring-site excitations and highlighting the importance of two-spin correlations.

Contribution

It provides a detailed analysis of magnetic excitation spectra in 1D cuprates, including the role of two-spin correlations in RIXS spectra beyond previous approximations.

Findings

Magnetic excitations involve both core-hole and neighboring sites.

RIXS spectra are expressed by one-spin and two-spin correlation functions.

Two-spin correlations can dominate in certain polarization and momentum conditions.

Abstract

We study the magnetic excitation spectra of L-edge resonant inelastic x-ray scattering (RIXS) from the spin singlet ground state in one-dimensional undoped cuprates. Analyzing the transition amplitudes of the magnetic excitations in the second-order dipole allowed process, we find that the magnetic excitations are brought about not only on the core-hole site but also on the neighboring sites. The RIXS spectra are expressed by the one-spin correlation function in the scattering channel with changing polarization, and the two-spin correlation function in the scattering channel without changing polarization. The latter could not be brought about within the so-called UCL approximation. We calculate these correlation functions on a finite-size ring. An application to the possible RIXS spectra in Sr_2CuO_3 demonstrates that the contribution of the two-spin correlation function could be larger than that of the one-spin correlation function in the \sigma polarization for the momentum transfer around the zone center.