Hidden Phases Revealed at the Surface of Double-Layered Sr3(Ru1-xMnx)2O7
  Double-layered Sr3Ru2O7 has received phenomenal consideration because it exhibits a plethora of exotic phases when perturbed. New phases emerge with the application of pressure, magnetic field, or doping. Here we show that creating a surface is an alternative and effective way to reveal hidden phases that are different from those seen in the bulk by investigating the surface properties of Sr3(Ru1-xMnx)2O7. Driven by the tilt distortion of RuO6 octahedra, the surface of Sr3Ru2O7 is less metallic than the bulk. In contrast, because of the vanishing of tilt and enhanced rotation with Mn-doping, the surface of Sr3(Ru0.84Mn0.16)2O7 is metallic while the bulk is insulating. Our result demonstrates that the electronic and structural properties at the surface are intimately coupled and consistent with quasi two-dimensional character. 
Chen Chen, Jisun Kim, V. B. Nascimento, Zhenyu Diao, Jing Teng, Biao   Hu, Guorong Li, Fangyang Liu, Jiandi Zhang, Rongying ...
cond-mat.str-el