Optimum thermal compensation axes in YIG and GaYIG ferrimagnetic spheres

A new measurement technique using a bandpass filter structure, called a filter-orienter, allows determination of magnetic properties of single crystal ferrimagnetic samples at arbitrary crystallographic directions. Materials properties can be conveniently measured over several octaves in field and over a considerable temperature rang. This technique was utilized to examine the ferromagnetic resonance thermal compensation axes of YIG and GaYIG spheres. An optimum thermal compensation axis was found which for GaYIG is an order of magnitude more stable over a multi-octave field range than the thermal compensation axis usually identified in the {110} crystal plane. Experimental results were explained by ferromagnetic resonance theory when -factor temperature dependence, propagation scattering, and other frequency perturbation effects were included.