On the temperature dependence of coercivity in bubble garnets films

Accurate measurements of magnetic aftereffect and coercivity in a magnetic bubble garnet are presented in the temperature range (-35°C, +60°C). The bubble material is an epitaxial Y_2.6Sm_0.4Ga_1.1Fe_3.9O₁₂ composition supporting 4 μm bubbles. The duration of the drive field pulse is varied between 100 ns and 2 ms. The curves taken at different temperatures of the minimum drive field duration versus its amplitude show similar hyperbolic shape. They are shifted towards small magnetic fields when the temperature increases. The experimental data are compared with a phenomenological model based on thermal activation. A good fit is obtained by taking the values at 20°C as a reference and comparing the experimental data with the calculated values for the different temperatures.