Berlin 2018 – scientific programme

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 7: Microstructure of thin films / TEM-based Nanoanalysis

KFM 7.4: Talk

Monday, March 12, 2018, 16:00–16:20, E 124

Dopant distribution and octahedral distortions at superconducting complex oxide bilayer interfaces — Y. Eren Suyolcu, Yi Wang, •Wilfried Sigle, Federico Baiutti, Georg Cristiani, Joachim Maier, Gennady Logvenov, and Peter A. van Aken — MPI für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart

We present results of doped lanthanum-cuprate (La2-xMxCuO4 (LMCO), x=0-0.4, M=Ca,Sr,Ba) systems where we systematically varied the dopant ionic radius while the dopant valence state was fixed [1]. Metallic LMCO layers were deposited on LaSrAlO4 followed by a second, insulating La2CuO4 layer, using atomic-layer-by-layer molecular beam epitaxy. Although none of the deposited layers is superconducting individually, the bilayer systems exhibit superconductivity. The critical temperature is found to depend on the dopant species. In order to elucidate possible mechanisms for interfacial superconductivity, the bilayer systems were structurally and chemically characterized in a probe-corrected JEOL JEM-ARM200F microscope. Perfect epitaxial growth is observed and dopants were found to be distributed depending on the dopant size. EELS spectrum imaging shows distinct differences among the three dopant species. Precise measurement of c-lattice parameters shows that the critical temperature is not, as expected, linearly related with the c-lattice parameter, i.e. with the distortion of oxygen octahedral [2]. [1] Y. E. Suyolcu et al., Sci. Rep. 7 (2017) 453. [2] Y. E. Suyolcu et al., Adv. Mater. Interfaces 1700737 (2017).