高磁敏伸缩薄膜的实验及理论研究

The rare earth-iron compound shows a giant magntostrictive effect, which arises an extensive interesting in recent years. These films have attractive potential uses in MENS, such as micro control system，micro driver and micro sensor. The main purpose of this research is how to improve the magnetostriction of TbFe or TbDyFe films prepared by magneto sputtering at a low applied magnetic field. The technological process, the structure and chemical composition, and the magnetic and magnetostrictive properties of the films are investigated experimentally. Meanwhile, the effect of the film's magnetic anisotropy on its magnetostriction λand dλ/dH at a low field are analyzed. The research shows that the as deposited films are amorphous that is maintained until annealed at 450℃ in vacuum , and a magnetic anisotropy vertical to the film because of the pillar-like structure. Therefore, the megnetostrictive coefficient λof as-deposited TbDyFe film is less than 50×10-6 at a applied field less than 150kA/m. The annealing treatment can cause the relax of the amorphous phases and the increase of the tensile stress, so the easy magnetic axis turns to parallel to the film when the annealed temperature reaches to 350℃. The change of the easy magnetic direction lead to the increase of the dλ/dH of TbDyFe film obviously. It is also founds that the adding of SmCo and Fe magnetic layers to the TbDyFe film can improve its magnerostrictiove properties at a low applied field effectively, but the different layers exert a different effect on the giant magnetostrictive film. The composite TbDyFe/SmCo film has a higher suscepertibility than TbDyFe film, so that the composite film shows as two timesλvalue as the TbDyFe film. While the exchange coupling effects arose by Fe layer and TbDyFe layer deposited alternatively may lead the great improvement in the magnetostrictive properties of TbDyFe/Fe multi-films. The λ and dλ/dH of TbDyFe/Fe are almost three times of that of TbDyFe film. In general term, the easy magnetic direction and the magnetization of the film play the importance roles in improving the properties of TbDyFe and TbFe films. The configurations, electronic structures, and magnetic properties of atomic mono- and multi-layers have been studied by using the first principle method based on the density functional theory.

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