Anisotropy control of magnetostrictive film patterns

The magnetic properties of Fe-based amorphous films are thought to be highly sensitive to strain due to the large saturation magnetostriction and soft magnetic properties exhibited by the films. This is why patterned FeCoSiB films exhibit a large variation in their high-frequency impedance when strain is applied. To increase the sensitivity of strain sensors, it is very important to control the magnitude of magnetic anisotropy. We propose a method to control the magnetic anisotropy by stress bias annealing. By applying stress during annealing, we were able to control the anisotropy along the width of the patterned film. A strain sensor using a transverse-anisotropy-induced film pattern exhibited a figure of merit F≈8300, while a sensor without anisotropy exhibited F of only 500