Structure, magnetic properties and giant magnetostriction studies in [Tb/Fe/Dy] n nano-multilayer film

Abstract

Tb/Fe/Dy] n nano-multilayer films, with precise composition of Tb 0.27 Dy 0.73 Fe 2 , were prepared by the multi-targets magnetron sputtering technique at room temperature (sample A) and 300℃ substrate temperature (sample B). Both of the nano-multilayer films show columnar structures perpendicular to the film plane according to the scanning electron microscopy results. The magnetic hysteresis loops and the giant magnetostriction (GMS) property of the two samples indicate the perpendicular anisotropy in them. In spite of the perpendicular anisotropy, both of the samples present GMS effect. In a very low applied field of 0.18 T, the GMS value in sample B is 89.3 ppm, which is about four times of that in sample A, 23.5 ppm. The good low-field GMS effect in sample B might attribute to the Laves phase of R-Fe 2 segregated from the amorphous matrix under the thermal annealing of the substrate. The relation between the magnetization process and GMS property of the perpendicular anisotropy nano-multilayer films is further investigated.Tb/Fe/Dy nano-multilayer film, giant magnetostriction effect, perpendicular anisotropy, Terfenol-D The magnetostriction effect is described most generally as the deformation of a body in response to the change in an external magnetic field, which was first discovered by Joule [1] . In the 1970s, the discovery of the giant magnetostriction and the progress in this field demonstrated its important value in applications. The Tb 0.27 Dy 0.73 Fe 2 (R-Fe 2 ) alloy, named Terfenol-D, is considered a useful material because of its giant magnetostriction (GMS) effect and low magnetocrystalline anisotropy at room temperature [2 -4] . The Terfenol-D GMS thin films, overcoming the shortcomings of the rod materials, have high electronic resistivity, high magnetic permeability, low magnetic hysteresis and weak magnetocrystalline anisotropy [5][6][7] . The GMS films with low field sensitivity are useful to the new type electromechanical transformation system [8][9][10] .Recently, much research has focused on the magnetic properties and the GMS of R-Fe 2 single films which are prepared by physical vapor deposition (PVD) [5][6][7][11][12][13][14][15][16] or pulsed laser deposition (PLD) [17,18] . Among the above methods, sputtering is the most economical solution for the massive production of GMS thin films prepared by the composite target [5,6,11,12,17] or mosaic target [14 -16] . However, the composition and performance stability still remain a problem for the above sputtered GMS thin films.In this work, we developed a simple way to prepare GMS nano-multilayer films with precise composition for stable GMS performance. Pure element targets Tb, Dy and Fe were used to deposit [Tb/Fe/Dy] n nano-multilayer films. The stable GMS performance of the films was achieved through controlling the thickness of each layer, which would be beneficial to the commercial applications. The GMS effect and magnetic properties of the [Tb/Fe/Dy] n nano-multilayer films were firstly investigated.