Simulation de topographies X (méthode de Lang) de domaines ferromagnétiques (Dijkstra–Martius) dans le fer–silicium

Abstract

X-ray section topographs of Dijkstra & Martius [Rev. Mod. Phys. (1953), 25, 146–150] magnetic domains in silicon–iron (2.4 wt. % Si) were simulated by means of a Fourier-transform numerical resolution of the Takagi–Taupin equations which describe X-ray propagation in distorted crystals. Two types of incident wave were used: a plane wave limited by a narrow slit at the entrance of the crystal, and a cylindrical wave centred at a distance of 10 to 50 cm from the crystal along the incident-beam direction. The agreement with experiments made by Schlenker & Kleman [J. Phys. C: Solid State Phys. (1971), 32 (Suppl.), 256–257] is good in the case of reflexions such as Co Kα11\bar 10 or Mo Kα1 1\bar 10, for which the magnetostrictive distortion field due to the junction of magnetic domains may be neglected, and only the discontinuity of the magnetostrictive distortion across a domain wall is taken into account in the computation. For the reflexion Mo Kα1 2\bar 20 the simulation does not exhibit the experimental contrast observed at the location of the 180° walls. A fair agreement with the experiment is, however, observed regarding the other features of the topograph.