Abstract
After rare-earth and transition-metal (RE-TM) thin films have been discovered to possess perpendicular anisotropy energy, it became the most popular candidate of magneto-optical recording media and appealed a lot of attention. Because RE-TM thin film has two opposite magnetic sub-lattices, we find many complex and interesting phenomenons. This thesis discusses perpendicular giant magnetoresistance in the sandwich structure TbFeCo/Cu/GdFeCo. Then we changed the component of magnetic layer to obtain the inverse giant magnetoresistance at room temperature and observed the changes of MR ratio. In addition, we altered the thickness of spacer to investigate the differences of magnetic properties. We discovered that the coercivity (Hc) of TbFeCo and GdFeCo oscillate with increasing the thickness of Cu. Due to this oscillation, we concluded that ferrimagnetic materials also behave RKKY effect. On the magnetic anisotropic exchange coupling, we found that the bias field of ferrimagnetic multilayers can be manipulated depending on the composition. If ferromagnetic layers were TM-TM, the bias field was negative. On the other hand, for RE-TM multilayers, the bias field become positive, which is quite different from ferromagnetic-antiferromagnetic coupling, and this can be explained by sublattice coupling.