Origin of the giant magnetic moments of Fe impurities on and in Cs films

TL;DR

This study investigates the origin of giant magnetic moments of Fe impurities in Cs films, revealing that Fe ions themselves are the primary source of magnetism due to localized 3d electrons, with results aligning with experimental data.

Contribution

It demonstrates that Fe impurities in Cs exhibit localized 3d electrons leading to large magnetic moments, differing from behavior in noble metals or Pd, and provides theoretical calculations supporting experimental observations.

Findings

Fe impurities in Cs have localized 3d electrons.

The magnetic moment mainly originates from Fe ions.

Calculated magnetic moments agree with experiments.

Abstract

To explore the origin of the observed giant magnetic moments ($\sim 7 \mu_B$) of Fe impurities on the surface and in the bulk of Cs films, we have performed the relativistic LSDA + U calculations using the linearized muffin-tin orbital (LMTO) band method. We have found that Fe impurities in Cs behave differently from those in noble metals or in Pd. Whereas the induced spin polarization of Cs atoms is negligible, the Fe ion itself is found to be the source of the giant magnetic moment. The 3d electrons of Fe in Cs are localized as the 4f electrons in rare-earth ions so that the orbital magnetic moment becomes as large as the spin magnetic moment. The calculated total magnetic moment of $M = 6.43 \mu_B$, which comes mainly from Fe ion, is close to the experimentally observed value.