Electron spin resonance study of low-dimensional magnetic properties of MnF2-CaF2 superlattices

Electron-spin-resonance (ESR) studies were performed on short-period MnF2-C aF2 superlattices on Si(111) grown by molecular beam epitaxy. In the case o f one to three MnF2 monolayers in the repeated unit of samples, angular dep endence of ESR linewidth revealed the behavior characteristic of a two-dime nsional (2D) magnet, where the linewidth minimum was observed for the angle between the plane normal and the external field of 55 degrees (magic angle ). At the same time, the antiferromagnetic transition of the bulk crystal a t around 67 K, observed for thick MnF2-layer films, is seen to have disappe ared in films of a few monolayers. These results indicate the development o f well-defined 2D magnetic layers in the present superlattice structures wi th a few MnF2 layers.