Structural and magnetic properties of electrodeposited Co Cu multilayers

A series of [Co(x ML)/Cu(17 ML)](100) multilayers were electrodeposited on Si(0 0 1) substrates covered with Cu seed layers. Magnetic hysteresis loops for films with x < 2 ML have sigmoidal shaper and the temperature dependen ce indicates a superparamagnetic behavior of the ultrathin Co layers. This behavior appears to be due to a discontinuity of the Co layers in the multi layer structure. In contrast, films with x > 2 ML have rectangular loops. I n-plane four-fold symmetry is observed for x > 4 ML, which reflects the mag netocrystalline anisotropy of the multilayers. The giant magnetoresistance effect is observed for x > 2 ML. (C) 1999 Elsevier Science B.V. All rights reserved.