### Session H30: Focus Session: Superconducting and Magnetic Oxide Superlattices and Films

8:00 AM–11:00 AM, Tuesday, March 17, 2009
Room: 334

Chair: Jak Chakhalian, University of Arkansas

Abstract ID: BAPS.2009.MAR.H30.7

### Abstract: H30.00007 : Anomalous Expansion of the Cu-Apical O Distance in Superconducting Cuprate Oxide Bilayers

10:00 AM–10:12 AM

Preview Abstract MathJax On | Off   Abstract

#### Authors:

Hua Zhou
(National Synchrotron Light Source, Brookhaven National Lab)

Yizhak Yacoby
(Racah Institute of Physics, Hebrew University)

Ronald Pindak
(National Synchrotron Light Source, Brookhaven National Lab)

Interfaces between complex oxides have received considerable attention due to the observation of fascinating quasi two- dimensional phenomena such as a high-mobility electron gas, interfacial ferromagnetism, and, recently, the observation of interfacial high-temperature superconductivity in epitaxially grown bilayers of metallic La$_{1.55}$Sr$_{0.45}$CuO$_{4}$ and insulating La$_{2}$CuO$_{4}$ on LaSrAlO$_{4}$ substrates$^{1}$. To help understand the mechanism underlying the observed interfacial superconductivity, we directly measured the 3D electron density of this epitaxial bilayer system with sub- atomic resolution using the Coherent Bragg Rod Analysis phase retrieval method$^{2}$. The Cu to apical O distance, which is believed to be a critical parameter controlling T$_{C}$, was found to expand dramatically from the substrate/film interface towards the surface. The correlation between structural features and interface transport properties will be discussed. $^{1}$A. Gozar et al., Nature, 455, 782(2008). $^{2}$Y. Yacoby et al., Phys. Rev. B, 77, 195426(2008).