Exploring small energy scales with x-ray absorption and dichroism

TL;DR

This paper uses x-ray absorption and dichroism techniques to measure small energy scales related to Ce 4f electrons in an ultrathin intermetallic compound, revealing the interplay of Kondo, crystal field, and magnetic interactions.

Contribution

It demonstrates the effectiveness of combining linear and circular x-ray dichroism to probe anisotropies and small energy scales in surface intermetallics.

Findings

All relevant interactions occur on small energy scales.

X-ray dichroism is highly sensitive to anisotropies.

The method effectively characterizes Ce 4f degrees of freedom.

Abstract

Soft x-ray linear and circular dichroism (XLD, XMCD) experiments at the Ce M$_{4,5}$ edges are being used to determine the energy scales characterizing the Ce $4f$ degrees of freedom in the ultrathin ordered surface intermetallic CeAg$_x$/Ag(111). We find that all relevant interactions, i. e. Kondo scattering, crystal field splitting and magnetic exchange coupling occur on small scales. Our study demonstrates the usefulness of combining x-ray absorption experiments probing linear and circular dichroism owing to their strong sensitivity for anisotropies in both charge distribution and paramagnetic response, respectively.