Observation of Spin Fluctuations in a High-Tc Parent Compound Using Resonant Inelastic X-ray Scattering

TL;DR

This study demonstrates the use of resonant inelastic soft x-ray scattering to observe and measure spin fluctuations and two-magnon excitations in the high-Tc parent compound CaCuO2, revealing new insights into its spin dynamics.

Contribution

First application of resonant inelastic soft x-ray scattering to detect spin fluctuations and measure magnetic properties in a high-Tc cuprate compound.

Findings

Detected magnon-magnon excitations via soft x-ray scattering.

Measured the two-magnon excitation energy and exchange parameter.

Established soft x-ray scattering as a new probe for spin dynamics in cuprates.

Abstract

We report the first observation of soft-x-ray scattering from spin fluctuations in a high-Tc parent compound. An antiferromagnetic charge transfer insulator, CaCuO2, was irradiated by Cu M-edge soft x-rays. Ultra-high resolution measurements of scattered intensity revealed magnon-magnon excitations, due to spin exchange scattering, as low-energy loss features. The process is analogous to optical Raman scattering. The spectra provide the first measurement of the two-magnon excitation energy and the antiferromagnetic exchange parameter in infinite-layer CaCuO2. The results reveal resonant inelastic soft x-ray scattering as a novel probe of the spin dynamics in cuprates.