Lattice parameter and magnetization variation of CrSi-coated substituted gadolinium iron garnet films induced by heat treatment

The property variations of CrSi-coated epitaxial garnet films of composition (Gd,Bi)
3
(Fe,Ga,Al)
5
O
12
have been studied after heat treatments in air. Lattice constant increases and variations of the saturation magnetization which are described by the variations of the compensation temperature were observed. The lattice constant increase is determined by the introduction of oxygen vacancies as well as by the redistribution of Ga and Al between the octahedral and the tetrahedral lattice sites. The latter mechanism is of main importance for the change of the magnetization. The oxygen vacancy concentration can be increased by reducing the garnet film thickness and is probably terminated by the development of a diffusion barrier layer at the CrSi-garnet interface.