Dresden 2006 – scientific programme
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DS: Dünne Schichten
DS 15: Thin magnetic films
DS 15.3: Talk
Wednesday, March 29, 2006, 16:30–16:45, GER 38
Substrate dependent Mn Valence Instability on La2/3Ca1/3MnO3 Thin Films — •Sergio Valencia1, Andreas Gaupp1, Alexei Erko1, Wolfgang Gudat1, Llibertad Abad2, Lluís Balcells2, and Benjamin Martínez2 — 1BESSY, Albert-Einstein-Str. 15, D-12489, Berlin, Germany — 2Institut de Ciéncia de Materials de Barcelona, Campus de la UAB, E-08193, Bellaterra, Spain
The Mn valence state of La2/3Ca1/3MnO3 (LCMO) thin films grown on SrTiO3 (STO), LaAlO3 (LAO) and NdGaO3 (NGO) substrates has been studied by X-ray absorption spectroscopy: The spectra at the Mn K and L edges and at the O K edge show the presence of a divalent Mn component, besides the expected Mn3+ : Mn4+=2/3:1/3 mixed valence state, for as-grown films related to the air exposure of the samples. For films grown on STO the Mn2+ presence is constant in time, while an increase of it is observed for films on LAO and NGO substrates. The origin of the Mn valence instability giving rise to the Mn2+ formation and the substrate dependent differences are discussed and tentatively related to the surface homogeneity of the substrate prior to the deposition of the material.