Structural analysis of the surface of bilayered ruthenate Sr$_{3}$Ru$_{2}$O$_{7}$

The bilayered ruthenate Sr$_{3}$Ru$_{2}$O$_{7}$ exhibits interesting structural properties. For example, in the bulk the in-plane lattice parameter $a$ expands while the out of plane lattice parameter $c$ contracts as temperature increases, accompanied by a rotation of RuO$_{6}$ octahedra. Remarkably, the broken translational symmetry at the surface causes a tilt of RuO$_{6}$ octahedra. The Low Energy Electron Diffraction (LEED) $I-V$ analysis shows that the tilt angle of RuO$_{6}$ is temperature dependent and hysteretic. The correlation between RuO$_{6}$ tilt at the surface, the surface thermal expansion, and the electrical properties were investigated using Scanning Tunneling Spectroscopy, (LEED)-$I-V, $and Scanning Electron Microscopy.