Measurement of magnetocrystalline anisotropy field and magnetostriction coefficient in garnet films

We report here on improvements to standard techniques for the measurement of the effective uniaxial anisotropy field HKE= HK-4πMs, the magnetocrystalline anisotropy field H1, and the magnetostriction coefficient λ111. Measurements were made on full wafer garnets in a wideband resonance spectrometer with a nonresonant microstrip transmission line, Advantages of this technique include higher sensitivity than a previously reported microstrip structure [1], no problems with coupled resonances in λ111measurements, as was reported by Vella-Coleiro [2] with a shorted waveguide, and ability to measure H1on full wafer garnets, in contrast to use of a resonant cavity [3] which requires dicing the wafer into small chips. In the H1calculation, the deviation of the magnetization from the applied field direction is considered. Accuracy of H1is better than ±10 Oe. A graphical method for determining H1is presented. Results on different material compositions which support 1 μm and 0.5 μm diameter bubbles are reported.