Physico-Chemical nanomaterials science

Investigation of the interface of Y3Fe5O12/Gd3Ga5O12 (YIG/GGG) structure, obtained by the liquid phase epitaxy
D. Sugak 1,2*, I.I. Syvorotka 1,2, U. Yakhnevych 1, Ya. Zhydachevskyy 1,3, 
A. Pieniążek 3, D. Włodarczyk 3, O. Buryy 1, S. Ubizskii 1, A. Suchocki 3,4 
1 Lviv Polytechnic National University, 12 Bandera st., Lviv, Ukraine.
*E-mail: sergii.b.ubizskii@lpnu.ua 
2 Scientific Research Company “Electron-Carat”, 202 Stryjska st., Lviv, Ukraine
3 Institute of Physics PAS, 32/46 Al. Lotnikуw, Warsaw, Poland
4 Institute of Physics, University of Bydgoszcz, 11 Weyssenhoffa st., Bydgoszcz, Poland

The liquid-phase epitaxy of single crystalline layers with the garnet structure is widely used technologies for obtaining of functional materials. The presence of defects in the epitaxial layers is a determining factor in their ability to work. One of the sources of defects is the interface between the epitaxial layer and the substrate. The study of YIG/GGG structures properties changes in the interface area is typically limited to the study of changes in the composition with depth along the growth direction (see e.g. [1]). In this case, the direction of sensing of changes also coincides with the direction of growth (perpendicular to the substrate). The purpose of this work was to study the properties changes of YIG/GGG structures by scanning with the probing radiation the interface area in the direction of growth, when the sensing beam itself propagates perpendicularly to the direction of growth (parallel to the substrate). The application of this approach is complicated by the fact that the thickness of the substrate is relatively small (~ 0.5 mm), and the total thickness of the structure usually does not exceed 1 mm. A 160 μm thick layer of YIG was grown on a 7 mm GGG substrate to achieve the goal. After this, a plate of 1 mm thickness was cut from the structure perpendicular to the plane of the grown layer. The plate surfaces were polished. The study of changes in properties during the transition through the interface from the substrate to the epitaxial layer was carried out with the help of: micro Raman spectroscopy, electron probe micro-analysis, optical spectroscopy. The lengths of the interface differ in different methods, which may be due to different methods sensitivity. According to the optical studies, the values of Fe absorption vary from the maximum in the epitaxial layer to the minimum in the substrate at a distance of about 20 μm, whereas, according to the micro-analysis, this distance is about 10 μm. The nature of the properties changes in the YIG/GGG structure interface area is discussed.

1. Dubs C., Surzhenko O., Linke R. et al. Sub-micrometer yttrium iron garnet LPE films with low ferromagnetic resonance losses // J. Phys. D: Appl. Phys. – 2017. -50. – P. 204005.