Depth and material sensitivity in magneto-optic nanostructures

Abstract

Magneto-optic (MO) methods are used for characterisation of magnetic ultrathin films and nanostructures. The paper deals with the sensitivity of the complex MO effect to films at different depths and to different materials in periodic multilayers and self assembled nanostructures. It is shown, that the basic principle and separation methods are the same for depth sensitive selectivity and the material sensitivity in nanostructures. Method of MO signal separation from different films and phases and the figure of merit used to quantify the MO ellipsometric selectivity of magnetic nanostructures is defined on the basis of linear matrix algebra. We review applicability of the method to separate MO contributions from (Au/Co) N , N = 2, 3; (Co/Au/NiFe/Au)10 multilayers; BiFeO3-CoFe2O4 self-assembled nanostructure; cobalt film on self-organised Au islands; and magnetically hard Fe nanoparticles near the surface of soft FeNbB amorphous ribbons.

Analysis of Magneto-Optical Hysteresis Loops of Amorphous and Surface-Crystalline Fe-Based Ribbons

“…The presented examples of hysteresis loops are similar to those measured on the thin multilayer systems (see, for example, [ 12 ]). Here, the authors introduced an ability of magneto-optics to distinguish two or more magnetically different phases of dissimilar anisotropies on the measured loop and called it depth and/or material sensitivity [ 13 ]. In the case of the amorphous Fe 80 Si 4 B 16 ribbon, the composed loops could theoretically come from the nanosized FeSi and FeB species (clusters) formed as a consequence of topological and chemical inhomogeneities [ 15 ].…”

“…It is a reason why this technique is highly effective also in investigations of thin-film multilayer systems [ 11 ]. Another important feature is the ability to distinguish the contributions from different depths or from different materials present in the system under investigation [ 12 , 13 ]. Due to the phase difference and additivity of magneto-optical effects, all detected contributions can be visualized on the measured hysteresis loop and separated using the linear matrix algebra.…”

“…Magneto-optical techniques were successfully applied in the surface studies of the CoFeSiB [ 14 ], FeSiB [ 15 ], or Fe-Nb-B [ 16 ] ribbon-type materials; the magnetically hard nanoparticles embedded in the amorphous matrix were detected on the wheel-side of the Fe 80.5 Nb 6.9 B 12.6 ribbon [ 13 ]. The consequence of partial surface crystallization was the formation of a bias field that shifted the hysteresis loops of strained Fe-Nb-B ribbons [ 17 ].…”