MEASURING TRANSPORT ANISOTROPY IN CU SI MULTILAYERS USING WEAK-LOCALIZATION/

We have determined the anisotropy of electron transport in a series of Cu/Si multilayers, by measuring their low-temperature transverse magn etoresistance due to weak localization (WL). For each sample, the meas urements were carried out for two different orientations of the applie d magnetic held: parallel and perpendicular to the plane of the sample film. Using an analysis based on an anisotropic 3D theory of WL we fi nd that the ratio of the in-plane and out-of-plane components of the e lectron diffusivity, delta = (D-xx/D-zz), varies from essentially 1 to more than 2 as the ratio of the Cu to Si nominal layer thicknesses is increased. X-ray diffraction studies indicate the formation of a copp er silicide at the interfaces of the multilayers, and a simple stratif ied conductor model based on this provides an estimate of the anisotro py that is consistent with that measured through the magnetoresistance . In some samples the magnetoresistance shows departures from the expe cted WL behaviour that are consistent with the presence of superconduc ting fluctuations.