Strongly coupled ferromagnetic resonances of Fe films

Abstract

The ferromagnetic resonance (fmr) fields of ultra-thin Fe films depend on the thicknesses of the films. Pairs of unequal films were prepared in which the resonances were resolved when the films were separated by as little as 1 nm of C. If the C spacing was made nominally zero a single fmr was observed. Depending on the background vacuum pressure, this single resonance occurs at two different fields. The low pressure sample seems to have structural coupling of the films to form one thick film. The fmr of the higher pressure sample qualitatively fits a model calculation of structurally separated films that are strongly magnetically coupled.