Mechanical, electrical and optical control of magnetization reversals and spin dynamics in extrinsic multiferroics
Résumé
Galfenol thin films have attracted a large amount of interest in the last two decades. Indeed, it is of interest to understand the fundamental mechanisms driving the strain and magnetic coupling in thin films. This study focuses on thin Fe0.81Ga0.19 (FeGa) films of thickness 5, 10, 20, and 60 nm deposited by sputtering onto glass substrates, PMN-PZT substrates and Aluminium foils. FeGa magnetostrictive properties were characterized using optical deflectometry. This first study reveals a remarkable thickness dependence, with an effective magnetoelastic coefficient decrease with an a thickness increase. A 10 nm Fe-Ga thin film was grown on Al kitchen foil and then mechanically strained under an isotropic configuration using spherical optical lenses. The FeGa MR properties under such a mechanical strain were determined. The results indicate the development of a random anisotropy character due to the bending. Under an electric field, a large converse magneto-electric effect for the Fe-Ga/PMN-PZT layered structure is observed. This effect is shown to be angular dependent. Finally, light control of static and dynamic magnetic properties in the Blue region is demonstrated. It is achieved with a CW laser or a LED.
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