Effect of broken symmetry on resonant inelastic x-ray scattering from undoped cuprates

Abstract

We study the magnetic excitation spectra of resonant inelastic x-ray scattering (RIXS) at the $L$-edge from undoped cuprates beyond the fast collision approximation. We analyse the effect of the symmetry breaking ground state on the RIXS process of the Heisenberg model by using a projection procedure. We derive the expressions of the scattering amplitude in both one-magnon and two-magnon excitation channels. Each of them consists of the isotropic and anisotropic contributions. The latter is a new finding and attributed to the long range order of the ground state. The presence of anisotropic terms is supported by numerical calculations on a two-dimensional spin cluster. We express the RIXS spectra in the form of spin-correlation functions with the coefficients evaluated on the cluster, and calculate the function in a two dimensional system within the $1/S$ expansion. Due to the anisotropic terms, the spectral intensities are considerably enhanced around momentum transfer $\text{q}=0$ in both one-magnon and two-magnon excitation channels. This finding may be experimentally confirmed by examining carefully the $\text{q}$-dependence of the spectra.

Latex, 13 pages, 9 figures, to be published in Journal of Physics:Condensed Matter

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Cited by in corpus (2)

• Resonant inelastic x-ray scattering study of entangled spin-orbital excitations in superconducting PrFeAsO0.7
• Multimagnon and multispinon $L_3$-edge RIXS spectra of an effective ${\tilde{J}}_1-{\tilde{J}}_2-{\tilde{J}}_3$ square lattice Heisenberg model