Localized Magnetic States of Fe, Co, and Ni Impurities on Alkali Metal Films

TL;DR

This study investigates the magnetic properties of Fe, Co, and Ni impurities on alkali metal films using XAS and XMCD, revealing localized atomic states and magnetic moments that diminish with cluster formation.

Contribution

It provides new insights into the localized electronic states and magnetic behavior of transition metal impurities on alkali metal surfaces.

Findings

Fe, Co, and Ni have localized d7, d8, and d9 states respectively.

Magnetic moments are large and atomic-like but decrease with cluster formation.

Ni impurities on Na are nonmagnetic with increased d10 character.

Abstract

X-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) have been used to study transition metal impurities on K and Na films. The multiplet structure of the XAS spectra indicates that Fe, Co, and Ni have localized atomic ground states with predominantly d7, d8, and d9 character, respectively. XMCD shows that the localized impurity states possess large, atomiclike, magnetic orbital moments that are progressively quenched as clusters are formed. Ni impurities on Na films are found to be nonmagnetic, with a strongly increased d10 character of the impurity state. The results show that the high magnetic moments of transition metals in alkali hosts originate from electron localization.