• DOI:10.1103/PhysRevB.77.035109
• Corpus ID: 119218698

Mott-Hubbard versus charge-transfer behavior in LaSrMnO4 studied via optical conductivity

@article{Gossling2008MottHubbardVC,
  title={Mott-Hubbard versus charge-transfer behavior in LaSrMnO4 studied via optical conductivity},
  author={Andreas Gossling and Maurits W. Haverkort and M. Benomar and H. F. Wu and Daniel Senff and T. Moller and Markus Braden and John A. Mydosh and Markus Gruninger},
  journal={Physical Review B},
  year={2008},
  volume={77},
  pages={035109}
}

• A. Gossling, M. Haverkort, +6 authors M. Gruninger
• Published 24 September 2007
• Physics
• Physical Review B

figuration 10Dq= 1.2 eV, eg= 1.4 eV, and t2g = 0.2 eV. The spectral weight of the lowest absorption feature at 1 – 2 eV changes by a factor of 2 as a function of temperature, which can be attributed to the change of the nearest-neighbor spin-spin correlation function across the Neel temperature TN = 133 K. Interpreting LaSrMnO4 effectively as a Mott-Hubbard insulator naturally explains this strong temperature dependence, the relative weight of the different absorption peaks, and the pronounced anisotropy. By means of transmittance measurements, we determine the onset of the optical gap opt = 0.4– 0.45 eV at 15 K and 0.1– 0.2 eV at 300 K. Our data show that the crystal-field splitting is too large to explain the anomalous temperature dependence of the c-axis lattice parameter by thermal occupation of excited crystal-field levels. Alternatively, we propose that a thermal population of the upper Hubbard band gives rise to the shrinkage of the c-axis lattice parameter.