Prediction of huge X-ray Faraday rotation at the Gd N_4,5 threshold

TL;DR

This paper reports the measurement of extremely large X-ray Faraday rotation in Gd near the N_4,5 threshold, revealing potential for nanoscale magnetic studies using magneto-optical effects.

Contribution

It provides the first experimental demonstration of giant Faraday rotation at the Gd N_4,5 threshold, enabling new nanoscale magnetic investigations.

Findings

Unprecedented short light absorption lengths down to 3 nm.

Faraday rotation of 0.7 degrees per atomic layer.

Potential for studying magnetic structures in nanosystems.

Abstract

X-ray absorption spectra in a wide energy range around the 4d-4f excitation threshold of Gd were recorded by total electron yield from in-plane magnetized Gd metal films. Matching the experimental spectra to tabulated absorption data reveals unprecedented short light absorption lengths down to 3 nm. The associated real parts of the refractive index for circularly polarized light propagating parallel or antiparallel to the Gd magnetization, determined through the Kramers-Kronig transformation, correspond to a magneto-optical Faraday rotation of 0.7 degrees per atomic layer. This finding shall allow the study of magnetic structure and magnetization dynamics of lanthanide elements in nanosize systems and dilute alloys.