Graded Orbital Occupation Near Interfaces in a La2NiO4-La2CuO4 Superlattice
Journal Article
·
· Physical Review. B, Condensed Matter and Materials Physics
X-ray absorption spectroscopy and resonant soft x-ray reflectivity show a nonuniform distribution of oxygen holes in a La{sub 2}NiO{sub 4}-La{sub 2}CuO{sub 4} (LNO-LCO) superlattice, with excess holes concentrated in the LNO layers. Weak ferromagnetism with T{sub c} = 160 K suggests a coordinated tilting of NiO{sub 6} octahedra, similar to that of bulk LNO. Ni d{sub 3z{sup 2}-r{sup 2}} 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.
- Research Organization:
- BROOKHAVEN NATIONAL LABORATORY (BNL)
- Sponsoring Organization:
- USDOE SC OFFICE OF SCIENCE (SC)
- DOE Contract Number:
- AC02-98CH10886
- OSTI ID:
- 1045888
- Report Number(s):
- BNL--96620-2011-JA; KC0201050
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Journal Name: Physical Review. B, Condensed Matter and Materials Physics Journal Issue: 15 Vol. 84; ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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