Surface and bulk structural properties of single-crystalline Sr3Ru2O7

We report temperature and thermal-cycling dependence of surface and bulk structures of double-layered perovskite Sr3Ru2O7 single crystals. The surface and bulk structures were investigated using low-energy electron diffraction (LEED) and single-crystal x-ray diffraction (XRD) techniques, respectively. Single-crystal XRD data is in good agreement with previous reports for the bulk structure with RuO6 octahedral rotation, which increases with decreasing temperature [similar to 6.7(6)degrees at 300 K and similar to 8.1(2)degrees at 90 K]. LEED results reveal that the octahedra at the surface are much more distorted with a higher rotation angle (similar to 12 degrees between 300 and 80 K) and a slight tilt [(4.5 +/- 2.5)degrees at 300 K and (2.5 +/- 1.7)degrees at 80 K]. While XRD data confirms temperature dependence of the unit-cell height/width ratio (i.e., lattice parameter c divided by the average of parameters a and b) found in a prior neutron-powder-diffraction investigation, both bulk and surface structures display little change with thermal cycles between 300 and 80 K.