Magnetostriction and its susceptibility of Fe 3.2 Tb alloy thin film deposited on polyurethane rubber substrate with low deformation resistance by using direct current magnetron sputtering process were investigated. When both residual gas pressure before argon sputtering and sputtering pressure of argon gas (5 N) were less than 5.0×10 -4 Pa and 2.0×10 -1 Pa, respectively, the thickness of the Fe 3.2 Tb films deposited was about 2.96 mm. The giant magnetostriction was found in the Fe 3.2 Tb alloy film on polyurethane rubber sheet, rather than on other polymer sheets. Giant motion strain of Fe 3.2 Tb alloy film largely depended on deformation resistance of substrate. (Received December 25, 2007; Accepted March 18, 2008) Keywords: magnetostriction, susceptibility, mover film, terbium, iron, direct current magnetron sputtering 緒 言

Magnetostrictive properties of Ar ion irradiated R Fe(R: Tb, Sm) thin films were studied with respect to residual stress. Film samples were prepared by a magnetron sputtering. The film composition was Tb 36 Fe 64 and Sm 27 Fe 73 with amorphous structures. After the deposition, film samples were irradiated by Ar ions with an energy of 10 keV and a current density of 27 80× 10 -2 A/m 2 up to 1×10 22 ions/m 2 . Magnetostrictive susceptibility of the Tb 36 Fe 64 film decreased with increasing ion current density by 55×10 -2 A/m 2 , however, improved with high current density above 70×10 -2 A/m 2 . Magnetostrictive susceptibility of Sm 27 Fe 73 increased with increasing ion current density up to 55×10-2 A/m 2 . This was caused by increase of compressive stress induced by Ar ion irradiation with low current density and stress relaxation by increased temperature during irradiation with high current density. The magnetic properties were found profoundly influenced by stresses induced by competitive factors such as irradiation damage and thermal annealing effect.

Ion plating (IP) process is a kind of vacuum evaporation process. In this study, Bunshah's triode type ion plating system was used for the film preparation. In this process dense plasma flux (～2.5 A) of ionized source materials can be dosed and deposited on a substrate. The flux of the source vapor is ionized by thermal electrons accelerated from melted evaporant to a positive electrode so called``probe''. Excess energy of vapor particles is able to control by applied bias voltage of``probe''. Fe has no Mg solid solution phase in equilibrium phase diagrams. In this study, Fe Mg thin films were prepared by an IP process. Investigated the relation between crystal structure and excess energy of particles with bias voltage. In all samples, a Fe body centered cubic structure was observed by X ray diffraction patterns. The lattice distortion changed with a change in applied bias voltage. These results were suggested that the excess energy of vapor particles was inputted more than the mixing enthalpy of Fe and Mg. At the same time lattice distortion energy in Fe increased with increasing Mg content. Film structures of samples were dependent on the kinetic energy of evaporated vapor particles changed by bias voltage.

Previously, as a means of expressing the effect of ion bombardment, we proposed an ion bombardment parameter P i based on the magnitude of the ion momentum and impingement ratio of Ar ions to metal particles. As a result the internal stress of the ferromagnetic films can be controlled by ion bombardment parameter P i . In this study, molecular mass effects with various sputtering gases such as Ar and Xe on magnetic thin films are quantitatively discussed with ion bombardment parameter P i . The Ni thin films were prepared by the D.C. magnetron sputtering process. Sputtering gases were using Argon (Ar) and Xenon (Xe). Plasma diagnostics was carried out by single Langmuir probe during the sputter deposition. The internal stress of the films varies linearly with ion bombardment parameter P i , regardless of the sputtering gas species. In addition, the magnetostrictive susceptibility of the film is also dependent on P i . Internal stress and magnetostrictive properties of Ni thin films could be controlled with ion bombardment parameter P i .

In this study, Fe In (Fe B system) alloys of ferromagnetic thin films with supersaturated indium concentration were prepared by a triode type ion plating process with dual vapor sources. The preparation of the supersaturated Fe In thin films was discussed on the basis of the effects of excess energy on the nanostructure of thin films. The kinetic energy of ions and the ionization rate in evaporation particles were measured using a Langmuir probe and a Faraday cup respectively. The excess energy of IP process increased with increasing applied bias voltage of discharge electrode. In X ray diffraction analysis, crystal structures of supersaturated film samples were shown to be a Fe bcc structures of Fe solid solution alloy. The ion plating process can control the solubility limit and nanostructure of Fe alloy thin films.