Dresden 2006 – wissenschaftliches Programm

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DS: Dünne Schichten

DS 15: Thin magnetic films

DS 15.3: Vortrag

Mittwoch, 29. März 2006, 16:30–16:45, GER 38

Substrate dependent Mn Valence Instability on La_2/3Ca_1/3MnO₃ 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 La_2/3Ca_1/3MnO₃ (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.