Polaronic orbital polarization in a layered colossal magnetoresistive manganite.
The striking anisotropy observed in Huang scattering distributions near the intense Bragg reflections of La{sub 1.2}Sr{sub 1.8}Mn{sub 2}O{sub 7} is shown to be the result of orbitally polarized polarons in the paramagnetic insulating state above T{sub c}. X-ray single-crystal diffuse scattering patterns from this bilayered colossal magnetoresistive manganite are calculated in terms of the polaronic local structure and compared with experimental measurements. At 300 K, the polaronic e{sub g} electrons occupy 'out-of-plane' (i.e., 3z{sup 2}-r{sup 2}) orbitals, leading to MnO{sub 6} octahedra that are Jahn-Teller elongated along the c axis, perpendicular to the perovskite layers. Between 300 K and T{sub c}, however, the 'orbital polarization' is shown to shift into the a-b plane (i.e., 3x{sup 2}-r{sup 2} and 3y{sup 2}-r{sup 2} orbitals), allowing the formation of nanoscale polaron correlations above T{sub c}.
- Research Organization:
- Argonne National Laboratory (ANL)
- Sponsoring Organization:
- SC; NIST; FOR
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 961070
- Report Number(s):
- ANL/MSD/JA-44369
- Journal Information:
- Phys. Rev. B, Journal Name: Phys. Rev. B Journal Issue: Jan. 1, 2003 Vol. 67; ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- ENGLISH
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