ANTIFERROMAGNETIC EXCHANGE AND ENHANCED MAGNETORESISTANCE IN GLASS FE-50 ANGSTROM CO11 ANGSTROM/CU(TCU)/CO77 ANGSTROM/CU10 ANGSTROM STRUCTURES/

Glass/Fe50 angstrom/Co11 angstrom/Cu/Co11 angstrom/Cu10 angstrom struc tures were sputtered in a high-vacuum system with a base pressure of 5 X 10(-8) Torr. The magnetoresistance (MR) reaches 8% at room temperat ure for t(Cu) = 10 angstrom with a saturation field of 700 Oe. For t(C u) = 22 angstrom the MR reaches 6.4% for a 200 Oe field. Our results a re analyzed in a semiclassical approach by solving the Boltzmann equat ion for the five-layer structure with lambda(Co) = 76 angstrom and lam bda(Cu) = 420 angstrom and using both interfacial and bulk spin-depend ent scattering. Interlayer coupling was checked by magneto-optical mea surements using the transverse Kerr-effect geometry. For t(Cu) = 10 an gstrom we observe zero-remanence magnetization curves with saturation fields around 1 kOe. For t(Cu) = 22 angstrom no evidence for macroscop ic antiferromagnetic coupling is observed since the hysteresis cycle i s almost square.