Identification of a new source of magnon relaxation in interface between epitaxial iron garnet ferrite films and GGG substrate

Abstract

We have investigated the intermediate layer between the gallium-gadolinium garnet substrate and the yttrium-iron garnet epitaxial film. This interlayer is characterized by a large magnetic moment at low temperatures, which leads to an anomalous dependence of the susceptibility and a shift in the magnetic resonance frequency upon cooling. This shift is much larger than might be expected due to magnetization anisotropy, substrate paramagnetic ions, and magnetostriction. We found that this interlayer plays a major role in magnetic relaxation processes in the temperature range below 50 K.