A method for anhysteretic magnetization and magnetostriction measurement of thin ferromagnetic films as a function of applied isotropic stresses

A method for measuring stress-dependent anhysteretic magnetization and magnetostriction in thin-film anisotropic ferromagnetic thin films or wires is described. This method uses a conventional vibrating-sample magnetometer combined with a specially designed loading fixture providing controlled uniaxial stresses on thin films and wires. Stresses are deduced from the characteristic resonant frequency of the sample in the fixture and verified via pulse propagation velocity measurement. Both indirect stress measurements are contactless, relying on remote vibration measurement using a laser Doppler vibrometer. These measurements have been demonstrated for membrane thicknesses down to 50 mu m and stresses up to 1 GPa, with estimated accuracy better than 0.2%. This method was applied to measure anhysteretic permeability and the magnetization curve of Ni-Fe alloys as functions of stress and temperature. This technique was also shown to be able to measure magnetostriction coefficient as a function of external magnetic field. (C) 2006 American Institute of Physics.