Non-linear actuation of cantilevers using giant magnetostrictive thin films

In the present paper, we report the first results concerning a centimetre cantilever driven through non-linear effects in thin magnetostrictive films. Bimorph centimetre beams (24 mm x 5 mm) were designed using 160 microns thick glass and 0.4 micron thick multilayer TbFe/Fe films deposited via RF sputtering, using several sputtering conditions. Dynamic magneto-elastic excitations were studied experimentally on the few eigenresonance modes of the cantilevers. Sub-harmonic excitation at half or one-third of the frequency of an eigenresonance mode has been achieved near the spin reorientation transition and the efficiency is as good as for eigenfrequency excitation. Specific magnetic properties of the samples led to a model of the thermodynamic potentials and behaviour of the excited resonator.