Nickelate heterostructures as a laboratory for many-body physics
Final Report Abstract
We report on advances in PLD growth, charge transport, and atomic structure determination of epitaxially strained nickelate heterostructures. Multilayer and superlattice systems exhibit multiple components with possibly different distortions and several interfaces which makes their structural determination difficult. In our project we accurately obtained the space group, octahedral rotation pattern and local lattice parameters from epitaxially strained LaNiO3-La(X)O3 ( X= Ga, Al) nickelate heterostructures by a combination of synchrotron x-ray diffraction and aberration-corrected TEM. In addition, we determined the exact atomic arrangement of different types of interfaces occurring in a LNO/LAO superlattice grown on LSAO. First, the substrateoverlayer interface structure was determined to be La/SrO-La/SrO-AlO2-LaO-(Al,Ni)O2-LaO-NiO2-LaO with the top LaO layer of the substrate not containing any Sr ions. This was achieved through a combination of atomic EELS mapping and hybridization mapping of the oxygen K edge fine structure. During the project we developed an approach than enables us to obtain spatially and momentum resolved energy loss spectra from thin Nickelate layers using nano-beam electron diffraction combined with electron energy loss spectroscopy. The spatially resolved MREELS spectra enable the characterization of spectra peak characteristics and their dispersion for various directions in the Brillouin zone.
Publications
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"Atomically resoved EELS mapping of the interfacial structure of epitaxially strained LaNiO3/LaAlO3 superlattices". Phys. Rev B 90, 195140 – Published 20 November 2014
N. Gauquelin, E. Benckiser, M.K. Kinyanjui, M. Wu, Y. Lu, G. Christiani, G. Logvenov, H.-U. Habermeier, U. Kaiser, B. Keimer and G. A. Botton
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"Lattice Distortion and octahedral rotations in epitaxially strained anisotropic modulation in Epitaxially Strained LaNiO3=LaAlO3 superlattices". Appl. Phys. Lett. . 104, 221909 (2014)
M.K. Kinyanjui, Y. Lu, N. Gauquelin, M. Wu, A. Frano, P. Wochner, M. Reehuis, G. Christiani, G. Logvenov, H.-U. Habermeier, G. A. Botton, U.Kaiser, B. Keimer, E.Benckiser
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“Revealing the atomic and electronic structure of a SrTiO3/LaNiO3/SrTiO3 heterostructure interface” Journal of Applied Physics 115, 103519 (2014)
Zaoli Zhang, S. Soltan, H. Schmid, H.-U. Habermeier, B. Keimer, and U. Kaiser
