Localized magnetic states of Fe, Co, and Ni impurities on alkali metal films

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 d(7), d(8), and d(9) 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 d(10) character of the impurity state. The results show that the high magnetic moments of transition metals in alkali hosts originate front electron localization.