Angular dependencies of thermal and nonlinear characteristics of spin wave signal processing

In the development of planar spin wave signal processing devices (delay lines, filters, resonators) based on thin yttrium-iron garnet (YIG) films, it is necessary to improve thermal stability of their characteristics and to enlarge their dynamic range of linearity. This can be done by selecting the orientation of the external bias magnetic field in relation to the film normal. Using the explicit approximate expressions for the spin wave spectrum in YIG films and taking into account the temperature dependencies of both saturation magnetization M0 and external bias magnetic field He we calculate the "thermostable" and the "linear" orientations of the bias magnetic field. It is shown herein that these two orientations coincide when the temperature dependence of the bias magnetic field is negligible. The proper orientation of the bias field improves the thermostability of a tunable YIG-film resonator by one order of magnitude in the whole range of tunability (from 5 to 10 GHz).