Experimental Control of the Structure in SrCuO₂ Ultrathin Films
P. C. Chiang1*, Y.-H. Chu2, J.-C. Yang3, J.-Y. Lin1
1Institute of Physics, National Chiao Tung University, Hsinchu, Taiwan
2Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan
3Institute of Physics, National Cheng Kung University, Tainan, Taiwan
* Presenter:P. C. Chiang
A two-dimensional (2D) CuO₂ plane is the basis for studying high-Tc superconducting cuprate. The formation of the CuO₂ plane in oxide thin films is limited by the strong electrostatic instability at the termination between the thin film and substrate. In this study, the ultrathin (1 - 20 uc) SrCuO₂ films were successfully grown on TiO₂-terminated SrTiO₃ substrates using pulsed laser deposition. The thickness-dependent structural transformation of the SrCuO₂ films was studied by polarized X-ray absorption spectroscopy (XAS) at the Cu L edge. XAS with theoretical calculation clearly distinguished chain-type structure and plane-type structure. XAS show that the component of out-of-plane direction decreases as the number of layer increase. In the 7uc SrCuO₂ ultrathin films, the out-of-plane XAS shown the same behavior as the infinite layer spectrum.

Keywords: SrCuO₂, monolayer copper oxide plane, structural transformation, superconductivity, oxygen