The surface of Sr2Ru0:9Mo0:1O4: a LEED and STM study

In the unconventional superconductor Sr2RuO4, substitution of a small amount of Mo for Ru destroys the superconducting state. We have used low energy electron diffraction (LEED) and scanning tunneling microscopy (STM) to study the cleaved (1 0 0) surface of the Mo-doped strontium ruthenate: Sr2Ru0:9Mo0:1O4. Excellent LEED patterns indicate a well-ordered surface similar to Sr2RuO4. The analysis of LEED-IðV Þ spectra revealed that the (Ru/Mo)O6 octahedra at the surface are rotated alternating clockwise and counterclockwise by 8.8 2.5 about the direction of the surface normal, which is identical to these on the surface of Sr2RuO4. But the high-resolution STM images of Sr2Ru0:9Mo0:1O4 show a surface fundamentally different from that of Sr2RuO4. The STM images are surprisingly inhomogeneous without clear atomic resolution. This indicates a local spatial roughness in the electronic structure induced by the Mo doping. 2003 Elsevier Science B.V. All rights reserved.