Measurement of thin film´s magnetostriction with piezoelectric ceramic substrates

The authors propose a method for measuring magnetostriction of magnetic thin films using piezoelectric ceramic substrates and feedback circuits. The main idea is to compensate for any bending along the sample´s length, using the inverse piezoelectric effect to change the length of the substrate by an amount equal to the change of length of the film due to magnetostriction. A feedback loop keeps the sample flat along the sample´s length. This method, being a null-measurement method, depends on very few parameters, and does not depend on any physical constant of the thin film being measured. It measures the magnetostriction directly and permits, in principle, far greater accuracy and reliability than conventional methods. The magnetostriction of Ni thin films was measured, and the values obtained were very close to the saturation magnetostriction of bulk Ni crystals