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 transmissi on 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 m agnetoresistance values were found to be typical of predominantly unia xial, ferromagnetically coupled multilayer films. The giant magnetores istance samples did not show a pronounced anisotropy. Rather than a co mplete antiparallel alignment of the magnetic layers at zero magnetiza tion, the giant magnetoresistance samples displayed a significant para llel alignment. Samples with moderate magnetoresistance values exhibit ed a mixture of the structures observed in the high and low magnetores istance films depending on the applied field orientation.