Electronic aspect and giant magnetoresistance in Co/Cu/Co sandwich structures

We have studied the electronic states in a non-magnetic spacer layer of Co/Cu/Co sandwich layers using the magneto-optical Kerr effect (MOKE) and x-ray photoemission and have found that they are discrete owing to the quantum size effect and appear approximately every 10.6 +/- 0.5 Angstrom. This coincides with the oscillation period of the saturation field. We connect them with the quantum minority-spin interface states near the Fermi level E(F) The magnetoresistance found in these sandwich layers has been calculated on the basis of the quantum size effect transport theory with the requirement that there exist quantum well states within individual layers or groups of layers. The results of the calculation and experiments have been discussed.