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During the last decades a range of experiments has become known which are based on spin dependent transport of electrons from one ferromagnetic film to another across a nonferromagnetic interlayer. Various processes like elastic or inelastic electron scattering, reflection and/or tunnelling can occur during the transition, which depend on the orientation of the electron spin with respect to the local magnetization. Due to this, oscillatory interlayer exchange coupling (IEC), Giant Magnetoresistance (GMR), and current induced magnetic excitations and switching (CIMS) are observed when the interlayer is metallic. For insulating and semiconducting interlayers, nonoscillatory IEC, tunnel magnetoresistance (TMR), and recently also CIMS has been observed. These phenomena will be discussed qualitatively using simple and transparent physical pictures. Emphasis will be on common features. Whereas oscillatory IEC across metals is rather well understood experiments on IEC and TMR across Si seem to contradict each other. Likewise- although GMR in Fe/CR structures was the first example for GMR, which was reported- its dependence on the thickness of the Fe layers in trilayer structures is at variance with experiments in multilayers. Some possible explanations will be discussed. It will also be shown how the switching bevaviour in CIMS in epitaxial Fe/Ag/Fe samples is modified by the presence of cubic crystalline anisotropy. Furthermore results on a superposition of normal and inverse CIMS in Fe/Ag/Fe/Cr/Fe structures will be reported. |