Measurement of saturation magnetostriction using novel strained substrate techniques and the control of the magnetic anisotropy

A simple new technique is described for the measurement of saturation magnetostriction in thin films deposited onto rigid substrates. The method is based on mechanically introducing a small curvature in the substrate either during the deposition (strained growth) or post-deposition. The strain-induced anisotropy is measured using the magneto-optical Kerr effect. Quantification of the film strain is obtained using optical interference and stylus measurements; coupled with mechanical finite-element modelling, this allows the saturation magnetostriction to be determined. No information about the mechanical properties of the substrate is required, and providing that the Young's modulus of the film is known accurately, the values of magnetostriction obtained are accurate and absolute. It is envisaged that the technique could be applied to a wide variety of films deposited onto commercially important substrates. Here, it is applied to amorphous films based on the METGLAS® 2605SC composition deposited onto glass and silicon substrates. A high degree of control is also demonstrated in tailoring the anisotropy field, by the technique of substrate straining.