[en] The authors examined the magnetostriction and coercive force of amorphous Tb-Fe films sputter-deposited under different conditions (rf input power, Ar gas pressure, Tb content, etc.). Here they discuss the possibility of obtaining both soft magnetic properties and a large magnetostriction in this system. Soft magnetic properties and large magnetostriction were obtained simultaneously in sputtered Tb-Fe thin films prepared with a Tb content of 45 to 50 at%, under an Ar gas pressure of 4 mTorr and with an rf input power of 200 W. This material has strong potential for use in magnetomechanical thin-film devices

[en] Fe_0.7Co_0.3 alloy has a large magnetostriction value and a high saturation magnetization. They have investigated the magnetostriction and magnetic properties of bcc Fe-Co-RE (RE a rare earth element) films. These films were prepared by dc triode sputtering. Addition of the RE elements Pr and Tb was found to increase the magnetostriction, while addition of the RE elements Ce, Nd, Sm and Er decreased it. These alloys film all exhibited high saturation magnetization values in excess of 200 emu/g. The high saturation magnetization appeared on addition of a small percentage of the RE element. Such films may be useful as soft magnetic materials

[en] Amorphous magnetostrictive wires fabricated by super-rapid quenching in water exhibit a remarkably stable Barkhausen effect and Matteucci effect in the as-prepared state. The Matteucci effect in as-prepared wire is under 1 mV. When the wire is drawn or made shorter than 70 mm, the Barkhausen effect vanishes. In this work, the amorphous magnetostrictive wire was cold drawn and then annealed under torsional stress; the wires obtained had a large Matteucci effect, as well as a large Barkhausen effect even when as short as 25 mm. These wires were used as devices for pulse generation. Their magnetic properties are studied

[en] The intermetallic compound Nd₂Fe₁₄B undergoes four-step phase transformations in a hydrogen atmosphere, namely, hydrogenation, decomposition, desorption and recombination. This phenomenon was observed in a study of the sintering behavior of an Nd-Fe-B magnet in atmospheric hydrogen gas. The sinter produced consists of crystalline grains ranging from extremely large to very small, and are magnetically isotropic (_iH_c approximately 7 kOe). The decomposition products first form fine crystalline grains and then grow into extremely large grains by an abnormal grain growth process when hydrogen is naturally desorbed. The forced low-temperature hydrogen desorption from the decomposition product creates powders with fine crystal grains (of order 0.3 μm), which have high coercivity (> 10 kOe). This process is called the HDDR process after the four steps involved. The addition of small amounts of elements such as Ga, Zr and Hf is effective for producing anisotropic magnet powders with good magnetic properties. It is now possible to prepare bonded magnets with (BH)_max = 18 MGOe (140 kJ/m³) from these anisotropic powders. This review describes the HDDR process and the uses of HDDR powders for anisotropic Nd-Fe-B bonded magnets and for full dense magnet production

[en] The purpose of this work was to clarify the magnetic properties, and in particular magnetoelastic effects, in Fe-rare earth amorphous alloys. In these experiments, the authors have investigated the changes in the magnetostriction with composition and temperature

[en] As trends continue toward lighter and more compact equipment, the preparation in thin film form of rare earth magnets with high energy products, by liquid quenching, sputtering and other methods, is being studied. In a previous report, the authors described the effect of the substrate temperature and film deposition rate on the magnetic properties of Nd-Fe-B films prepared by dc diode sputtering and reported that by choosing the film fabrication conditions appropriately, it was possible to obtain films with an anisotropy in the thickness direction. However, the films thus prepared had a small coercivity, and also suffered from poor reproducibility of magnetic characteristics. In the study reported, in consideration of the reproducibility of film properties, the authors used a dc triode sputtering method to prepare films, and investigated the effect of the annealing conditions on the film coercivity

[en] Great expectations are being placed on Bi:YIG films, with their prominent magnetooptical properties, as materials for use in magnetooptical disks and optical isolators. As part of efforts aimed at practical application, numerous studies are being conducted to increase the Faraday rotation and reduce the absorption coefficient of such films. It has been reported that the optical properties of Bi:YIG films are affected by the atmosphere in which the films are annealed. However, these reports dealt with LPE-grown films, which contained numerous additives. In this work, the authors have investigated the effect of the annealing atmosphere on the magnetooptical properties of Bi:YIG films prepared by RF sputtering. Their results are reported

[en] The authors have applied a multi-pass packed-rolling technique to the production of anisotropic Nd-Fe-B-Cu powders from rapidly quenched ribbons. Analysis of the packed-rolling process shows that densification proceeds from the surface of the packed powder-compact and crystallographic alignment proceeds more rapidly at the center. Rolling to a reduction in ribbon thickness of greater than 80% results in a uniform material with a high (BH)_max of up to 38 MGOe. The present paper discusses the alignment mechanism, taking into consideration the internal stress distribution inside the powder compact under rolling pressure

[en] Highly pure single crystals of YIG were obtained by an FZ method, and a remarkable photoinduced change in permeability was observed. The permeability of samples held at a temperature of 77 K was decreased by more than 90% by illumination. The photoinduced change remained, to some extent, at temperatures up to about 260 K. By annealing at 1100 degrees C (in an oxygen atmosphere for six hours) in the sample preparation stage, the magnitude of the effect was reduced to 40%. After samples at 77 K were strongly illuminated, the loss factor below 5 kHz showed a pair of peaks, in contrast with the flat curve for unilluminated samples on warming to 300 K. The activation energies corresponding to the peaks were found to be 0.3 and 0.1 eV. The mechanism of the effect is discussed in relation to relaxation processes related to these peaks, and F⁰ centers, or oxygen vacancies with two trapped electrons, are though to play an essential role

[en] The authors have been trying to clarify the origin of perpendicular magnetic anisotropy (K_{perpendicular}) of amorphous rare earth-transition metal ally films, by means of changing the kind of rare earths and their composition systematically for Fe or Co based binary systems. In this study, they used Gd, Dy, and Er as the rare earth elements, and investigated the temperature dependence of K_{perpendicular} and the saturation magnetization M_s, as well as the film magnetostriction