Giant magnetostrictive multilayers (invited)

Multilayers combining exchange-coupled giant magnetostrictive materials (amorphous TbFe) and materials with large magnetic polarizations (FeCo or FeCoBSi) exhibit significant improvements in terms of low field magnetostriction and magnetostrictive susceptibility compared to state-of-the-art giant magnetostrictive single layer materials, due to the polarization enhancement and the anisotropy reduction in such multilayers. The magnetic, magnetostrictive, and mechanical properties of these multilayers can be engineered by varying their layer thickness ratios. With TbFe/FeCo multilayers saturation magnetoelastic coupling coefficients exceeding 25 MPa in combination with a magnetic saturation field of 20 mT and a coercive field of 2 mT can be obtained, while in TbFe/FeCoBSi multilayers the hysteresis almost vanishes but at the expense of the magnetostriction. Furthermore these multilayered materials show $ΔE$ and magnetoresistance effect, which should allow the realization of smart thin film actuators.