CC BY 3.0 UnportedUrbanik, G.Hänke, T.Hess, C.Büchner, B.Ciszewski, A.Hinkov, V.Lin, C.T.Keimer, B.2018-06-012019-06-282009https://doi.org/10.34657/1687https://oa.tib.eu/renate/handle/123456789/4348We performed scanning tunneling microscopy and spectroscopy on untwinned crystals of underdoped YBa2Cu3O7- δ at δ = 0.4. A comprehensive statistical analysis of our topographic data indicates a doping dependent cleaving behavior of this material. We find in particular that at δ = 0.4 the material primarily cleaves in multiples of one unit cell along the c-axis with a high corrugation of the topmost layer. Our data suggest that the low temperature cleaving mainly results in a disruption of the CuO chain layers involving a redistribution of the layer atoms onto the two cleaving planes. In a few instances, fractional step heights (in terms of the c-axis lattice constant) are observed as well. Scanning tunneling spectroscopy reveals that such fractional steps connect surfaces which differ significantly in their tunneling conductance.application/pdfenghttps://creativecommons.org/licenses/by/3.0/530Cell membranesCopper oxidesScanningScanning tunneling microscopySpectroscopyReport