The simultaneous measurement of energy and linear polarization of the scattered radiation in resonant inelastic soft x-ray scattering

TL;DR

This paper introduces a new device for measuring the linear polarization of scattered soft X-ray radiation in RIXS experiments, enhancing spectral interpretation and demonstrating its application on a high-Tc superconductor.

Contribution

It presents the first implementation of a polarization measurement device in a high-resolution RIXS spectrometer, improving spectral analysis capabilities.

Findings

Successfully installed and characterized the polarization measurement system.

Demonstrated the system's use on a high-Tc cuprate at the Cu L3 edge.

Achieved a detailed understanding of polarization effects in RIXS spectra.

Abstract

Resonant Inelastic X-ray Scattering (RIXS) in the soft x-ray range is an element-specific energy-loss spectroscopy used to probe the electronic and magnetic excitations in strongly correlated solids. In the recent years, RIXS has been progressing very quickly in terms of energy resolution and understanding of the experimental results, but the interpretation of spectra could further improve, sometimes decisively, from a full knowledge of the polarization of incident and scattered photons. Here we present the first implementation, in a high resolution RIXS spectrometer used to analyze the scattered radiation, of a device allowing the measurement of the degree of linear polarization. The system, based on a graded W/B4C multilayer mirror installed in proximity of the CCD detector, has been installed on the AXES spectrometer at the ESRF; it has been fully characterized and it has been used for a demonstration experiment at the Cu L3 edge on a high-Tc superconducting cuprate. The loss in efficiency suffered by the spectrometer equipped with this test facility was a factor 17.5. We propose also a more advanced version, suitable for a routine use on the next generation of RIXS spectrometers and with an overall efficiency up to 10%.