Eur. Phys. J. B 69, 483-489 (2009)
https://doi.org/10.1140/epjb/e2009-00198-y

Surface of underdoped YBa₂Cu₃O_7-δ as revealed by STM/STS

¹ Institute of Experimental Physics, University of Wroclaw, 50-204 Wroclaw, Poland
² Leibniz-Institute for Solid State and Materials Research, IFW-Dresden, 01171 Dresden, Germany
³ Max Planck Institute for Solid State Research, Stuttgart, Germany

Corresponding author: ^a gurbanik@ifd.uni.wroc.pl

Received: 26 October 2008
Revised: 29 March 2009
Published online: 9 June 2009

Abstract

We performed scanning tunneling microscopy and spectroscopy on untwinned crystals of underdoped YBa₂Cu₃O_7-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.