A model was developed to predict the temperature dependent changes in the local magnetic ordering based on spin-polarized Mn K-edge measurements of La1-xCaxMnO3. With this model, one can ascertain the change in local ordering that occurs on transiting the magnetic ordering temperature. Parallel local density approximation (LDA) and LDA+U computations are used to label the symmetries of the unoccupied bands, determine the degree of electron correlation and to provide a direct comparison with the band ordering predicted by the temperature dependent spin-polarized measurements. The spin magnetic moment and ordering of the t2g and eg states are also determined. We find that the occupied t2g orbitals are always ordered with lobes near 45° to the local Mn-O directions. The Mn K-edge main line splitting is discussed in terms of the effective spin-polarized charge density. The oxygen hole contribution to the net magnetic moment is seen to be important. We survey the spin-polarized x-ray absorption near-edge spectra of a large group of manganese oxides and show the general trends in the main line spin splitting as a function of valence.
|Physical Review B - Condensed Matter and Materials Physics
|Published - 2003
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics