Asymmetry of hysteresis properties of the layers in double layered exchange coupled magnetic films

The switching of amorphous double layered binary and ternary rare-earth (RE) cobalt alloy films with perpendicular anisotropy in the layers is studied. Specimens are prepared by ion-plasma sputtering in Ar atmosphere on glass or silicon substrates. Hysteresis loops are measured from both sides of the film by the polar Kerr effect method. An X-ray diffractometer and an Auger electron spectrometer are used for structure investigation and composition analysis. A microdispersed polycrystalline RE oxide region with a thickness of about 10 nm are detected both on the free surface of the film and on the interlayer boundary. It is found that neither oxidized interlayer nor the surface influences the switching of the upper layer, but that hysteresis loops from down one strongly distort when exposition time exceeds five minutes. An explanation of the pecularities of the switching mechanism of oxidation of the film surface is proposed