Effect of heat treatment on the magnetic properties of substituted YIG

Heating and subsequent quenching of aluminum and gallium substituted YIG changes the distribution of the cations among the
d
- and
a
- sites in the garnet lattice and, consequently, the magnetization of the material. This effect can be utilized to adjust the magnetization to a particular desired value and to obtain matching samples for microwave devices. This ion redistribution process was studied in detail on single crystal specimens with different amounts of substitution for two purposes: 1) to determine the influence of the heat treatment on the magnetocrystalline anisotropy and 2) to establish the relation which describes the cation migration between the two sites. Therefore, the saturation magnetization and the magnetic anisotropy were measured between 4.2 and 300°K on samples which experienced a variety of heat treatments with subsequent quenching or slow cooling from temperatures between 800 and 1200°C.