Thanks to high resolution and polarization analysis, resonant inelastic x-ray scattering (RIXS) magnetic spectra of La2CuO4, Sr2CuO2Cl2 and CaCuO2 reveal a rich set of properties of the spin 1/2 antiferromagnetic square lattice of cuprates. The leading single-magnon peak energy dispersion is in excellent agreement with the corresponding inelastic neutron scattering measurements. However, the RIXS data unveil an asymmetric lineshape possibly due to odd higher order terms. Moreover, a sharp bimagnon feature emerges from the continuum at (1/2,0), coincident in energy with the bimagnon peak detected in optical spectroscopy. These findings show that the inherently complex spin spectra of cuprates, an exquisite manifestation of quantum magnetism, can be effectively explored by exploiting the richness of RIXS cross sections.
@article{arxiv.2102.04078,
title = {Multiple-magnon excitations shape the spin spectrum of cuprate parent compounds},
author = {Davide Betto and Roberto Fumagalli and Leonardo Martinelli and Matteo Rossi and Riccardo Piombo and Kazuyoshi Yoshimi and Daniele Di Castro and Emiliano Di Gennaro and Alessia Sambri and Doug Bonn and George A. Sawatzky and Lucio Braicovich and Nicholas B. Brookes and Jose Lorenzana and Giacomo Ghiringhelli},
journal= {arXiv preprint arXiv:2102.04078},
year = {2021}
}