Graded orbital occupation near interfaces in a La2NiO 4-La2CuO4 superlattice

S. Smadici, J. C.T. Lee, J. Morales, G. Logvenov, O. Pelleg, I. Bozovic, Y. Zhu, P. Abbamonte

Research output: Contribution to journalArticlepeer-review

Abstract

X-ray absorption spectroscopy and resonant soft x-ray reflectivity show a nonuniform distribution of oxygen holes in a La2NiO 4-La2CuO4 (LNO-LCO) superlattice, with excess holes concentrated in the LNO layers. Weak ferromagnetism with Tc=160 K suggests a coordinated tilting of NiO6 octahedra, similar to that of bulk LNO. Ni d3z2-r2 orbitals within the LNO layers have a spatially variable occupation. This variation of the Ni valence near LNO-LCO interfaces is observed with resonant soft x-ray reflectivity at the Ni and Cu L edges, at a reflection suppressed by the symmetry of the structure, and is possible through graded doping with holes, due to oxygen interstitials taken up preferentially by inner LNO layers. Since the density of oxygen atoms in the structure can be smoothly varied with standard procedures, this orbital occupation, robust up to at least 280 K, is tunable.

Original languageEnglish (US)
Article number155411
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume84
Issue number15
DOIs
StatePublished - Oct 11 2011

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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