Magnetoconductivity of ultrathin epitaxial Ag films on Si(111)7x7 at low temperatures

Ultrathin epitaxial Ag films on Si(111) 7x7 have been shown to have at appr oximately 4 K a very low conductance, whereas at 100 K the metallic conduct ivity is evident. Therefore the magnetoconductance has been used to identif y the different scattering mechanisms. The conductance and the magnetocondu ctance have been measured in situ with four-point probes in van der Pauw ar rangement. For thicknesses from 1.8 to 20 ML different scattering mechanism s have been revealed in the temperature range from approximately 4 to 20 K and magnetic fields from -4 T to +4 T perpendicular to the sample surface. Whereas for films thicker than 3 ML the weak localization and antilocalizat ion provide a complete description, the thinnest films show properties not yet described quantitatively by any theory. [S0163-1829(99)01703-8].