Impact of microstructure on the Mn valence of La2/3Ca1/3MnO3 thin films
Abstract
The oxidation state of Mn in La2/3Ca1/3MnO3 thin films grown on single crystalline SrTiO3 , LaAlO3 and NdGaO3 substrates has been analyzed by soft x-ray absorption spectroscopy. The spectra at the Mn-L2/3 edges and at the O-K edge indicate the presence of a Mn2+ component, besides the expected Mn3+/Mn4+ mixed valence state being characteristic for this material. It is observed that the appearance of the Mn2+ component is closely related to the exposure of samples to ambient atmosphere. The divalent Mn spectral contribution IMn2+ to the Mn L2/3 -edge spectra is almost thickness independent but exhibits a clear dependence on the substrate used. The origin of the Mn valence instability giving rise to the Mn2+ formation and the substrate dependent behavior is discussed in connection with the different microstructure of the samples.
- Publication:
-
Physical Review B
- Pub Date:
- May 2007
- DOI:
- 10.1103/PhysRevB.75.184431
- Bibcode:
- 2007PhRvB..75r4431V
- Keywords:
-
- 78.70.Dm;
- 75.47.Lx;
- 75.70.-i;
- 71.20.-b;
- X-ray absorption spectra;
- Manganites;
- Magnetic properties of thin films surfaces and interfaces;
- Electron density of states and band structure of crystalline solids