Electronic transport in ultrathin magnetic multilayers

In-plane electronic transport in ultrathin metallic magnetic structures composed of two ferromagnetic films separated by a nonmagnetic metallic spacer is analyzed theoretically, with particular attention paid to the role of quantum size phenomena and interface roughness in the giant magnetoresistance (GMR) effect. Within the one-band model we predict oscillations in the resistivity and GMR as a function of the spacer thickness. In general, two different oscillation periods are found. It is also shown that the spin-dependent scattering due to interface roughness can enhance or reduce the GMR effect generated by the spin-dependent scattering on impurities or other defects inside the films. Long-range in-plane structural correlations of the interface roughness reduce its role in the GMR effect.