Electron microscope observations of the magnetic structures in magnetoresistive multilayer films

A detailed investigation of the magnetic domain structures present in Cu-based magnetoresistive multilayers was carried out using transmission electron microscopy. The Cu thickness was varied to give multilayer films exhibiting a wide range of magnetoresistance values. The domain structures and magnetization reversal processes in samples with low magnetoresistance values were found to be typical of predominantly uniaxial, ferromagnetically coupled multilayer films. The giant magnetoresistance samples did not show a pronounced anisotropy. Rather than a complete antiparallel alignment of the magnetic layers at zero magnetization, the giant magnetoresistance samples displayed a significant parallel alignment. Samples with moderate magnetoresistance values exhibited a mixture of the structures observed in the high and low magnetoresistance films depending on the applied field orientation. © 1994 IOP Publishing Ltd.