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Amorphous ribbons of an alloy with the composition (Tb0.33Fe0.67)0.98B0.02, which exhibit good magnetostrictive properties at low magnetic fields, are bonded with a phenol-based binder to fabricate bulk composites. Efforts to determine optimum fabrication parameters are made by examining magnetic and mechanical properties of bulk compacts obtained at various fabrication conditions. From the binder content dependence of magnetostriction and compressive strength, the optimum binder content is estimated to be about 4.3 wt %, taking into account magnetostrictive and mechanical properties and the necessity of reducing nonmagnetic binder content. The two properties of magnetostriction and compressive strength vary nearly linearly with the compaction pressure; as the compaction pressure varies from 0.25 to 1.0 GPa, magnetostriction decreases but compressive strength increases, making it difficult to determine the optimum compaction pressure. A magnetostriction of 493 ppm (at 1.1 kOe) is achieved from the present bulk composites, together with a high dλ/dH (sensitivity of magnetostriction with applied magnetic field) of 1 ppm/Oe.

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The magnetic and structural properties of as-sputtered nanocrystalline Fe–Al–O films, fabricated by a magnetron sputtering apparatus, are investigated as a function of the sputtering input power and the contents of Al and oxygen. A nanocrystalline Fe88.5Al3.5O8.0 film is found to have 4πMs of 18.2 kG, Hc of 0.6 Oe, μeff of 4600 up to 100 MHz. These excellent soft magnetic properties and high frequency characteristics result from nanocrystalline structure, high electrical resistivity, and moderate anisotropy field. These values are sufficient to apply to a high-density recording head.

We have carried out the magnetization study of melt-spun ribbons of (Tb0.33Fe0.67)1−xBx (x=0, 0.02, 0.05, 0.1, and 0.15) alloys. The temperature dependence of magnetization was measured using a superconducting quantum interference device and a vibrating-sample magnetometer during heating from 5 to 800 K, with an applied field of either 10 or 50 kOe. The present study shows the existence of noncollinear magnetics structures. From an analysis of the approach to saturation magnetization, the average magnetic moment μa, random anisotropy field Hr, and local random anisotropy constant KL have been extracted. It is found that μa decreases from 1.68 (x=0) to 1.33 μB (x=0.15) and KL increases with increasing B concentration. This result suggests that the addition of B seems to increase the random anisotropy and hence to decrease the magnetic order, resulting a sperimagnet with large spread angle.