Efforts were made to obtain anisotropic thin-film magnets at low substrate temperature. This is an important criterion for practical applications such as to build motors. The influence of substrate materials as well as film thickness on the c-axis orientation were studied. It has been shown that thin-film magnets with the easy axis of magnetization normal to the film plane could be deposited at a substrate temperature of around 450 °C by choosing the composition near the line from Nd13Fe76B11 to Nd13Fe70B17 in the ternary phase diagram. It was found that the anisotropic film magnets could be also deposited on the metallic substrate. The c-axis orientation tended to be isotropic with an increase in film thickness. The obtained results were used to fabricate a milli-size motor by depositing 20-μm-thick Nd–Fe–B films on a silicon steel disk substrate of 5-mm diam. The milli-size motor exhibited a torque of 0.8 g mm at a rotational speed of 3000 rpm.

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An overview of advances of the amorphous wire magnetics over the past 27 years with discoveries of extremely sensitive magnetic effects such as the large Barkhausen effect, the Matteucci effect and the magnetoimpedance effect and their successive applications to security sensor tags, pen‐inputting computer tablets and electronic compasses for mobile phones in commercial productions is presented. An important new topic of biocell magnetic field sensing in vitro and human physiological magnetic field sensing in vivo using a 10 pT amorphous wire magnetoimpedance sensor is also shown that would be improved using thinner glass‐covered amorphous wires. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Isotropic Nd-Fe-B thick film magnets were prepared by a high-speed pulsed laser deposition method followed by a post annealing. The deposition rate of 90 m/h could be successfully achieved, and a pulse annealing was adopted as the post annealing process in order to enhance coercivity. Use of a substrate heating system under the high deposition rate enabled us to obtain anisotropic thick films with ( ) max of approximately 120 kJ/m 3 , which show the potential for an improvement in the properties of the micromachines. Novel micromachines comprising the isotropic films were introduced.

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Articles you may be interested inEffect of surface domain structure on wall mobility in amorphous microwires J. Appl. Phys. 105, 07A310 (2009); 10.1063/1.3068481Magneto-optical investigation of high-frequency electric current influence on surface magnetization reversal in Co-rich amorphous microwires

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