Long-range exchange interactions in epitaxial layered magnetic structures

Since the discovery of antiferromagnetic (AF) type interlayer coupling in 1986 numerous systems have been investigated. Generally, it is found that the coupling of ferromagnetic films separated by an interlayer oscillates as a function of the interlayer thickness between ferro (F)- and AF-type and the transition zones are characterized by 90 degrees-type coupling. The oscillation periods are in agreement with a theory that attributes the microscopic origin of the coupling to an indirect exchange of the ferromagnetic layers via the electrons of the interlayer. For the 90 degrees-type coupling various mechanisms have been proposed but the situation is still unclear. We would like to present here a condensed overview of the field and illustrate the development with some own results.