Crossover from two to one dimension inin situgrown wires of Pb

Using a novel fabrication technique, we have studied the metal-insulator transition in in situ grown wires of Pb with cross-sectional areas as small as ${10}^{\mathrm{-}13}$ ${\mathrm{cm}}^3$. We find that as we cross over into the 1D regime, fluctuations dominate the superconducting transition. Although existing fluctuation models work well at the larger cross-sectional areas, there is systematic deviation as the wires become smaller. We speculate that this may be due to 1D Coulomb correlation effects.