FABRICATION AND SIMULATION OF MAGNETOSTRICTIVE THIN-FILM ACTUATORS

Sputter-deposited magnetostrictive films present an interesting opport unity to realize actuators in microsystems, as they offer features lik e contactless high-frequency operation, simple actuator designs and a cost-effective manufacturing technique. Amorphous magnetostrictive fil ms of the binary compound SmFe as well as of the ternary compound TbDy Fe have been prepared by d.c. magnetron sputtering using either a mult itarget arrangement with pure element targets or cast composite-type t argets. Depending upon the composition and the sputtering conditions, particularly upon the bias voltage, amorphous films with a giant magne tostriction of about 250 ppm (-220 ppm) at 0.1 T and 400 ppm (-300 ppm ) at 0.5 T for TbDyFe (SmFe) and an adjustable magnetic easy axis can be prepared. In view of their applications in microsystem technologies (e.g., pumps, valves, positioning elements), these films have been te sted in cantilever arrangements. The design of the actuators, such as the lateral patterning of the magnetostrictive films, has been modulat ed by means of finite-element calculations. For double-clamped beams o r clamped membranes, these calculations reveal that lateral patterning of the magnetostrictive films is essential in order to obtain large d eflections.