Localization and Dimensionality in Nonsuperconducting Bi sub (2+x) Sr sub (2-y) CuO sub (6+-delta) Crystals.
13 March 1989
Measurements of transport, tunneling and magnetoconductivity in nonsuperconducting BISR single crystals (x,y ~0.2) show two-dimensional (2D) localization within the CuO sub 2 planes. The weakening of 2D localization is found to be by itself insufficient for superconductivity. Negative magnetoconductivity, evidence for the onset of superconducting fluctuations, occurs only when transport perpendicular to the planes gives rise to extended states in three dimensions.