Effects of reduced dimensionality on the magnetic properties of ultrathin (Co/Cu)[111] films

Due to the collective nature of the electronic interactions responsible for the appearance of ferromagnetic ordering, a strong influence of reduced di mensionality is to be expected in ultrathin magnetic films and heterostruct ures. In this article we review a number of experimental results covering s everal of those effects. For instance, the coercivity of ultrathin Co/Cu(11 1) films increases continuously up to similar to6 monolayer Co thickness. W e show that this behavior is related to the thickness dependence of the Cur ie temperature of these low-dimensional samples. Moreover, magnetic anisotr opy and interlayer exchange coupling are also strongly affected by the stru ctural features. Because of their smaller interfacial roughness, films grow n with the aid of a surfactant Pb layer exhibit perpendicular magnetization up to larger thicknesses than those grown without Pb. With respect to the exchange coupling, the first ones show oscillatory magnetic coupling and co mplete antiferromagnetic coupling for both perpendicular and parallel magne tization between Co layers, while for films grown without Pb there is alway s some amount of ferromagnetic coupling between Co layers. (C) 2001 America n Institute of Physics.