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 H
KE
= H
K
-4πM
s
, the magnetocrystalline anisotropy field H
1
, and the magnetostriction coefficient λ
111
. 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 λ
111
measurements, as was reported by Vella-Coleiro [2] with a shorted waveguide, and ability to measure H
1
on full wafer garnets, in contrast to use of a resonant cavity [3] which requires dicing the wafer into small chips. In the H
1
calculation, the deviation of the magnetization from the applied field direction is considered. Accuracy of H
1
is better than ±10 Oe. A graphical method for determining H
1
is presented. Results on different material compositions which support 1 μm and 0.5 μm diameter bubbles are reported.