lego-like construction of Ruddelsden-Popper surfaces using octahedra building blocks.*

The surface of Ruddelsden-Popper (RP) ruthenates provides a rich playground to study the emergent phenomena originating from the coupling of lattice, charge and spin, mediated through RuO₆ octahedron network. Because of the octahedra rotation, Sr₂RuO₄ surface shows a (√2 ×√2)R45° reconstruction. In addition to enhanced bulk-like octahedral rotation, Sr₃Ru₂O₇ surface displays octahedral tilt as well. In this work, using ultra-high-vacuum cleaved surface of Sr₂RuO₄ as a platform, we have sequentially grown different number of SrRuO₃ unit cells (u.c.) thin films, to mimic progression of “surface layer/s” of Sr₂RuO₄ to those of higher RP ruthenates (i.e. one u.c. is equivalent to Sr₃Ru₂O₇, two u.c. for Sr₄Ru₃O₁₀ surface and so on). Combining low energy electron diffraction with transmission electron microscopy, we systematically study the evolution of the lattice structure and discuss their properties.