Statics and dynamics in giant magnetostrictive Tb/sub x/Fe/sub 1-x/-Fe/sub 0.6/Co/sub 0.4/ multilayers for MEMS

Abstract

In the present paper, giant magnetostrictive thin films have been investigated for future microelectromechanical systems (MEMS) purposes. For this goal, flexural and torsional motions have been studied in low field anisotropic giant magnetostrictive (GMS) single domain state (SDS) exchange-coupled TbFe/FeCo multilayers (ECML). The magnetoelastic (ME) coefficient b γ,2 depend strongly on the ECML structures, compositions, and sputtering deposition parameters. Giant magnetostrictive Multilayers with a high b γ,2 (18M P a for T bF e 2 /F e 0.6 Co 0.4 compared to 11M P a for T bF e 2 /F e) were obtained with or without an in-plane easy axis with a controlled direction, and without any annealing post-process. Dynamical excitations of the actuators have been investigated under various conditions. An enhancement up to a factor 5 of the oscillations compared to the TbFe/Fe multilayers is observed with the possibility to tune the flexural/torsional dynamical behavior of these cantilevers. The corresponding very large dynamical ME susceptibility of these improved uniaxial ECML gives the possibility to control GMS MEMS with further reduction of the excitation field down to a few oersteds.

Stress-mediated magnetoelectric memory effect with uni-axial TbCo2/FeCo multilayer on 011-cut PMN-PT ferroelectric relaxor

“…7 In 2010, we proposed and patented an innovative memory device called MELRAM (Magneto-ELectric Random Access Memory) based on a composite structure composed of a nanometer sized magnetostrictive material embedded in a piezoelectric matrix. [8][9][10][11] In particular, we showed that the competition between an external magnetic field and uni-axial magnetic anisotropy can be used to define two perpendicular equilibrium positions for magnetization 12,13 and that the application of stress can trigger the switch between both positions in a deterministic fashion. A macroscopic device using a commercial piezoelectric stack provided an experimental proof of concept of this memory element 14 and demonstrated the writing principle using piezoelectric stress.…”

Planar Magnetostrictive Micromechanical Actuator

“…Another approach for magnetostrictive actuators is the vertical stacking of materials with different magnetostrictive coefficients (multilayers) to gain an out-of-plane deflection in presence of a magnetic field. These actuators can be designed to exhibit small dimensions by utilizing microfabrication technologies, but lack of high stroke displacements and blocking forces [8], [9].…”

MEMS magneto-mechanical microvalves (MMMS) for aerodynamic active flow control

“…In this last approach, the goal is to enhance the sensitivity of the actuator to the driving field by taking profit of the magnetic instability. It is also possible to propose new strategies of actuation based on dynamic properties of the system in the vicinity of the SRT [11,12].…”