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Orbital degree of freedom in single-layeredLa1−xSr1+xMnO4: Doping- and temperature-dependent rearrangement of orbital states

Authors :
Dario Arena
Bernd Büchner
S. Tokumitsu
Stefan Schuppler
Georg Roth
M. Merz
Yves Idzerda
P. Reutler
J. Dvorak
Source :
Physical Review B. 74
Publication Year :
2006
Publisher :
American Physical Society (APS), 2006.

Abstract

Oxygen $1s$ near-edge x-ray absorption spectroscopy and x-ray diffraction investigations on ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{1+x}\mathrm{Mn}{\mathrm{O}}_{4}$ $(0\ensuremath{\leqslant}x\ensuremath{\leqslant}0.5)$ single crystals evidence a doping- and temperature-dependent redistribution of ${e}_{g}$ electrons between ${d}_{3{z}^{2}\ensuremath{-}{r}^{2}}$, ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$, and ${d}_{3{x}^{2}\ensuremath{-}{r}^{2}}∕{d}_{3{y}^{2}\ensuremath{-}{r}^{2}}$ orbitals: For undoped $\mathrm{La}\mathrm{Sr}\mathrm{Mn}{\mathrm{O}}_{4}$ the ${e}_{g}$ electrons predominantly reside on ${d}_{3{z}^{2}\ensuremath{-}{r}^{2}}$ orbitals, nevertheless a small amount of charge carriers is found on in-plane ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ orbitals. These in-plane electrons are gradually transferred to the ${d}_{3{z}^{2}\ensuremath{-}{r}^{2}}$ states upon cooling. Sr doping, however, does not only provide holes to the system but also induces a continuous transfer of electrons from ${d}_{3{z}^{2}\ensuremath{-}{r}^{2}}$ to ${d}_{3{x}^{2}\ensuremath{-}{r}^{2}}∕{d}_{3{y}^{2}\ensuremath{-}{r}^{2}}$ orbitals and, finally long-range charge-exchange-type orbital ordering develops for ${\mathrm{La}}_{0.5}{\mathrm{Sr}}_{1.5}\mathrm{Mn}{\mathrm{O}}_{4}$ below $T\ensuremath{\leqslant}225\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. The data indicate a short-range orbital ordering for the intermediate doping range.

Details

ISSN :
1550235X and 10980121
Volume :
74
Database :
OpenAIRE
Journal :
Physical Review B
Accession number :
edsair.doi...........895500243a0a55e6682375697095786c
Full Text :
https://doi.org/10.1103/physrevb.74.184414