DIMENSIONAL CROSSOVER IN THE LOW-TEMPERATURE TRANSPORT-PROPERTIES OF ANNEALED AMORPHOUS FE SI MULTILAYERS/

We present measurements of the low-temperature, T < 20 K, conductance, G(T), of amorphous Fe/Si multilayers as a function of the temperature at which they are annealed, T(ann). concentrate on two of the multila yers which have 10 angstrom thick Fe layers and different Si layer thi cknesses (32 and 40 angstrom). At low temperatures, the quantum correc tions to G(T) are logarithmic indicating that the individual Fe layers are in the two dimensional limit and are not coupled to one another. Annealing the samples at, temperatures as low as 150-degrees-C drives the interdiffusion of the Fe and Si layers. This interdiffusion leads to stronger coupling between the conducting layers and a reduction in their conductances. After an anneal at 350-degrees-C, the conductance of the multilayer sample with the thinner Si layers rises sharply and G(T) acquires a square-root temperature dependence. This behavior sign als a crossover from two to three dimensional electronic transport.