Magnetic properties and microstructure of giant magnetostrictive TbFe/FeComultilayers

Magnetostrictive multilayer films which combine exchange coupled giant magn etostrictive materials (amorphous Tb0.4Fe0.6) and soft magnetic materials w ith large polarizations and considerable magnetostriction (crystalline Fe0. 5Co0.5) were prepared by magnetron sputtering. The microstructure and the m agnetic properties of these multilayers were investigated as a function of the annealing temperatures and the corresponding film stresses. Giant magne toelastic coupling coefficients (or magnetostrictions) are achieved at low fields, due to the magnetic polarization enhancement in such multilayers, t he optimized stress state, and a suitable microstructure. For these optimiz ed Tb0.4Fe0.6 (7 nm)/Fe0.5Co0.5(9 nm) multilayers a saturation magnetoelast ic coupling coefficient of 27.5 MPa at 20 mT and a coercive field of 2 mT h as been achieved. (C) 1998 American Institute of Physics. [S0021-8979(98)40 811-9].