Effect of Yttrium Iron Garnet Composition on the Properties of Y3Fe5O12/GaAs Thin-Film Structures

Owing to their unique electromagnetic and magneto-optical properties, yttrium iron garnet (YIG, Y3Fe5O12) and solid solutions based on it are used in producing thin-film structures for magnonics, a new area in spintronics. The ability to determine the exact chemical composition of synthesized YIG is a critical issue for not only the matrix elements (Fe and Y), but also impurity components (Li, Be, B, Na, Mg, Al, Si, P, K, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Rb, Sr, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, La, Ce, Sm, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Tl, Pb, Bi, Th, and U), because the presence of impurities at a level above 10–2 wt % causes a considerable broadening of its ferromagnetic resonance (FMR) line and impairs properties of thin-film structures. In this work, we demonstrate that joint use of inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS) under appropriate analysis conditions allows one to obtain accurate results and determine a wide range of elements. We describe specific features of the preparation of thin-film structures containing Y3Fe5O12 film on a gallium arsenide substrate by a new, nonepitaxial method proposed by us and demonstrate the effect of the impurity composition of YIG on the structure and properties of such films. To prevent interfacial interaction between Y3Fe5O12 and GaAs during film crystallization, an AlOx barrier layer was first grown on the substrate by sputter deposition. We have studied FMR spectra of Y3Fe5O12/AlOx/GaAs films produced by different techniques and shown that the FMR linewidth of the films produced via sputtering of YIG single crystals is 30 to 40 Oe smaller than that of the films containing impurity elements.