Application of Electrochemical Hydrogen Loading Technique for Internal Stress Control in Magnetostrictive Thin Films

Magnetostrictive thin films plays important roles on the developments in the field of sensors, vibration energy harvesting devices, and building actuators. Amorphous Sm-Fe thin films are known to have a large negative magnetostriction. It is supposed that increasing internal stress leads to improvement of the magnetostrictive susceptivity, from practical point of view. In case of a metallic thin films clamped to a rigid substrate, it is generally wellknown that the in-plane compressive stress arises during hydrogen absorption, due to its volume expansion. During hydrogen absorption, this effect takes place as long as no stress release happens, such as film detachment or plastic deformation. In other words, the in-plane stress can be tuned by loading controlled small amount of hydrogen, to improve the magnetostrictive properties of negative magnetostrictive films. This work aims to investigate the possibility of the electrochemical hydrogen loading technique for tuning the in-plane stress for the sputter deposited Sm-Fe films as well as the evaluation of its adhesion.