| Summary: | 碩士 === 國立海洋大學 === 光電科學研究所 === 89 === When a magnetic substance is exposed to a magnetic field, the magnetization process due to the rotation of magnetic moment makes the lattice deformation. Then, the magnetic material's shape is forced to change. This change is directly proportional to applied magnetic field, and then the deformation up to saturation. To measure magnetostriction of a bulk magnetic material, the deformation is so big that it is can be measured easily. We can use the strain gauges to measure. However, the deformation caused by the saturation magnetostriction of a thin-film material is very small. Hence, its experimental determination is not an easy task.
For the magnetic thin film, we set up an optical-cantilever device to measure saturation magnetostriction of a magnetic thin film. The measuring principle of the cantilever is that when there is a deformation of a bimorph and the reflected laser light path is caused to make some displacements, we maesure the curvature of the substrate and then calculate the saturation magnetostriction of the magnetic thin film. The thickness of the thin film is 1500Å in this experiment. We have found that maximum capability of the device is about (Å) .Finally, we have measure a λs of 78 Permalloy by this device. We found that the measured result is almost the same as reported from other papers. We believe that our device is quite reliable inλs measurement.
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