Mystery of the Alkali Metals: Giant Moments of Fe and Co on and in Cs films

Abstract

Thin films of Cs are covered with $\frac{1}{100}$ of a monolayer of Fe or Co. Then the impurities are covered with several atomic layers of Cs. The magnetization of the films is measured by means of the anomalous Hall effect. The magnetization follows a Brillouin function with a magnetic moment of about 8 Bohr magnetons for Co on the surface and in the bulk of the Cs. For the Fe impurities, a magnetic moment of 7 Bohr magnetons is observed. These large moments suggest that the $3d$ impurities polarize the conduction electrons of the Cs similar to the giant moments in Pd.