Effect of surface magnetism on the x-ray spectra of hollow atoms

TL;DR

This study demonstrates that surface magnetism can be detected through x-ray emission spectra of highly charged ions interacting with a sample, revealing changes during magnetic phase transitions without external magnetic fields.

Contribution

It provides new evidence linking surface magnetism detection to x-ray spectra analysis of ion-surface interactions, resolving previous controversies.

Findings

Surface magnetism detection via x-ray spectra is possible without external magnetic fields.

The ion population changes during the ferro-paramagnetic phase transition.

The findings clarify previous contradictory results in ion-surface interaction studies.

Abstract

We present evidence that the detection of surface magnetism without the application of an external magnetic field is possible by studying the x-ray emission of highly charged ions interacting at grazing incidence with the sample. Measuring the 3 keV $n=2 \to 1$ transition in the interaction of Ar\textsuperscript{17+} with a nickel sample at various temperatures gives access to the $n=2$ ion population. The latter evolves from a half-filled to a full shell during the ferro-paramagnetic phase transition of the sample, with the ferromagnetic phase reflecting the filling blocking due to Pauli principle. This finding puts an end to a longstanding controversy arising from contradictory studies of ion--surface interaction using Auger spectroscopy.