Study of depth-dependent local structures in thin films by grazing-incidence X-ray absorption spectroscopy

C. E. RODRÍGUEZ TORRES

CAMPINAS

Congreso; 22ª Reunião Anual de Usuários do LNLS- CHARLA INVITADA; 2012

Nowadays many different industrial technologies require knowledge of surface, near surface and interface properties of bulk materials, thin films and multilayered structures on a nanometric scale. In this regard, a clear understanding of the macroscopic properties requires a substantial knowledge of their dependence on layer thickness and the complex microstructural effects frequently localized at the interface film/substrate or at the surface of the film. Such effects can be studied using experimental techniques able to peer selectively into the depth of the films. The versatility of geometries and detection schemes enables the association of X-ray Absorption Spectroscopy (XAS) to advanced experimental setups, providing the material science with a renewed original insight. Grazing incidence (GI) XAS is already used worldwide and its sensitivity in probing in-depth properties by tuning the grazing incidence is becoming a reliable issue. As the sampling depth is strongly dependent on the incident angle, near the critical angle for total reflection, GIXAS is used under controlled incidence to get information about the local order depth profiles in samples with different thicknesses. Here we present results combining XAS with resolved GI, using setups available at the XRF fluorescence beamline of the Brazilian Synchrotron Light National Laboratory (LNLS) located in Campinas, SP (Brazil), to clarify the thickness-dependent magnetic properties of nanometric oxide films such as Co doped SnO2 and Zn ferrites. Partial results in Zn ferrites were recently published by our group in [1]. References [1] Evidence of defect-induced ferromagnetism in ZnFe2O4 thin films. C. E. Rodríguez Torres, F. Golmar, M. Ziese, P. Esquinazi, S. P. Heluani. Phys. Rev. B 84, 064404 (2011).