Spin waves and magnetoresistance in exchange coupled layered magnetic structures

Spin waves in single-crystal double layers (grown by molecular beam epitaxy) of b.c.c. iron with interlayers of f.c.c. gold and b.c.c. chromium have been investigated by inelastic-scattering experiments. The growth of the interlayers was analysed and characterized by Auger electron spectroscopy. The appropriate spin wave spectra have also been calculated theoretically on the basis of a macroscopic description. From comparison of the experimental and numerical data we have determined the interlayer exchange constant A12 as a function of the interlayer thickness d0. For gold interlayers with sufficiently small d0 the interlayer coupling was found to be ferromagnetic, whereas for chromium interlayers of appropriate thickness it was antiferromagnetic. In the latter case also strong magnetoresistance effects were observed. We compare results from experiments at room temperature and low temperatures.