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 6.7 6 ° at 300 K and 8.1 2 ° at 90 K . LEED results reveal that the octahedra at the surface are much more distorted with a higher rotation angle 12° between 300 and 80 K and a slight tilt 4.5 2.5 ° at 300 K and 2.5 1.7 ° 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.