Dependence of the Magnetic Properties of Y3Fe5−xGaxO12 and Y3Fe5−xAlxO12 on Thermal History

Abstract

The saturation magnetization, Curie temperature, compensation point, and ferromagnetic resonance linewidth of Y₃Fe_5−xM_xO₁₂, M=Ga or Al, depend upon the thermal history of the sample. For example, a single crystal of YGaIG, x=1.26, will exhibit a room‐temperature 4πM_s between 220 and 88 G as it is quenched from temperatures ranging downward from 1275°C and finally slow‐cooled to room temperature. T_c will decrease 3.5°C. The results can be explained by assuming the Ga or Al concentration on octahedral sites increases with increasing temperature. The direction of the change in Curie temperature is predicted by Gilleo's theory. The results are important to the control of magnetic properties of garnets in applications requiring closely matched samples.