X-ray fluorescence induced by standing waves in the grazing-incidence and grazing-exit modes: study of the Mg–Co–Zr system

Yuchun Tu (1) , Yanyan Yuan (1) , Karine Le Guen (1) , Jean-Michel André (1) , Jingtao Zhu (2) , Zhanshan Wang (2) , Françoise Bridou (3) , Angelo Giglia (4) , Philippe Jonnard (1)

1 LCPMR - Laboratoire de Chimie Physique - Matière et Rayonnement
2 IPOE - Institute of Precision Optical Engineering [Shangai]
3 Laboratoire Charles Fabry / Optique XUV
4 IOM - CNR Istituto Officina dei Materiali

We present the characterization of Mg-Co-Zr tri-layer stacks by using x-ray fluorescence induced by x-ray standing waves, both in the grazing incidence (GI) and grazing exit (GE) modes. The introduction of a slit in the direction of the detector improves the angular resolution by a factor 2 and significantly the sensitivity of the technique for the chemical characterization of the buried interfaces. By observing the intensity variations of the Mg Kalpha and Co Lalpha characteristic emissions as a function of the incident (GI mode) or detection (GE mode) angle, we show that the interfaces of the Si/[Mg/Co/Zr] x30 multilayer are abrupt, whereas in the Si/[Mg/Zr/Co] x30 multilayer a strong intermixing occurs at the Co-on-Zr interfaces. The explanation of this opposite behaviour of the Co-on-Zr and Zr-on-Co interfacesis given by the calculation of the mixing enthalpies of the Co-Mg, Co-Zr and Mg-Zr systems, which shows that the Co-Zr system presents anegative value and the two others positive values. Together with the difference of the surface free energies of Zr and Co, this leads us to consider the Mg/Zr/Co system as aMg/Co x Zr y bi-layer stack, with x/y estimated around 3.5.

Mots clés: X-ray standing wave; X-ray fluorescence; multilayer; interface

Domaines: Autre [cond-mat.other]

Yuchun Tu, Yanyan Yuan, Karine Le Guen, Jean-Michel André, Jingtao Zhu, et al.. X-ray fluorescence induced by standing waves in the grazing-incidence and grazing-exit modes: study of the Mg–Co–Zr system. Journal of Synchrotron Radiation, 2015, 22 (6), pp.1419-1425. ⟨10.1107/S1600577515016239⟩. ⟨hal-01224951v2⟩