94 Journal of Magnetism and Magnetic Materials 82 (1989) 94-98 North-Holland, Amsterdam STRESS AND FIELD INDUCED MAGNETIC ANISOTROPIES IN Co-RICH AMORPHOUS ALLOYS J. GONZALEZ Departamento de Fisica de Materiales, Facultad de Ciencias Qulmicas, Universidad del Pals Vasco, 20009 San Sebastidn, Spain and K. KULAKOWSKI 1 Laboratoire Louis NJel, CNRS, 166 X, 38040 Grenoble-Cedex, France Received 19 June 1989 Stress+field induced magnetic anisotropies by current annealing in (Col_xFex)75SilsB10 (x= 4, 5, 6, 8, 10 and 12), (Co0.95Fe0.05)75Si~B25_ x (x =10, 12.5 and 15) and (Co0.95Fe0.05)90_xSixB10 (x =10 and 15) amorphous alloys have been studied. The magnetic field during the annealing was applied either transverse or longitudinal to the axis ribbons. Stress+ field induced magnetic anisotropies increase as a function of the annealing temperature to reach a maximum value ( ~- 340 o C) and then they decrease. While the direction of stress + transverse field induced anisotropy is transverse to the axis ribbon, the direction of stress + longitudinal field induced anisotropy may be longitudinal or transverse to the axis ribbon. A study of the influence of the composition on the direction and intensity in these anisotropies has been performed. 1. Introduction The possibility of inducing magnetic anisotro- pies in metallic glasses has been determined by Luborsky et al. [1], where they performed field annealings on Fe-rich amorphous alloys for an- nealing temperatures less then the Curie tempera- ture. They explained the field induced magnetic anisotropy in a similar way to the induced mag- netic anisotropy in crystalline alloys. Later, Niel- sen et al. [2] and Hilzinger [3] showed that stress annealing in metallic glasses could induce mag- netic anisotropy even at annealing temperatures above the Curie temperature. Moreover, this ani- sotropy may be induced in zero-magnetostrictive amorphous alloys and its origin is, therefore, dif- ferent to that of field induced anisotropy. Re- 1 On leave from the Institute of Physics and Nuclear Tech- niques, Academy of Mining and Metallurgy, Cracow, Po- land. cently, stress + field annealings have been per- formed in several amorphous alloys [4,5] and it has been shown, first, that stress + field induced magnetic anisotropy cannot be supposed to be the simple sum of the stress induced anisotropy and the field induced anisotropy. Second, it seemed that the direction of the stress + field induced anisotropy was fixed by the direction of the mag- netic field applied during the annealing and the applied tensile stress may enhance this anisotropy. But this hypothesis was found to be untrue when a study in similar way to ref. [5] was carried out in the sample (Co0.94Feo.06)75SilsB10 and the stress + longitudinal field induced anisotropy was trans- verse to the axis ribbon [6]. However, we have decided to perform stress + field induced mag- netic anisotropies (when the magnetic field is ap- plied either longitudinal or transverse to the axis ribbons) in several alloys of Co-Fe-Si-B (Co-rich) in order to explain the possible mechanisms re- sponsible for the origin of these anisotropies. 0304-8853/89/$03.50 © Elsevier Science Publishers B.V. (North-Holland Physics Publishing Division)