Journal of Magnetism and Magnetic Materials 294 (2005) 245–251 Coercivity and induced magnetic anisotropy by stress and/or field annealing in Fe- and Co- based (Finemet-type) amorphous alloys C. Miguel, A. Zhukov, J.J. del Val, J. Gonza´lez à Departamento de Fı´sica de Materiales, Facultad de Quı´mica, Universidad del Paı´s Vasco, Paseo Manuel de Lardizabal 3, 20018 San Sebastia ´n, Spain Available online 15 April 2005 Abstract Uniaxial magnetic anisotropy has been induced in amorphous Fe 73.5 Cu 1 Nb 3 Si 15.5 B 7 (Fe-rich) and (Co 77 Si 13.5 B 9.5 ) 90- Fe 7 Nb 3 (Co-rich) ferromagnetic alloys by annealing under stress and/or magnetic field. Such anisotropy plays a crucial role on the magnetization process and, consequently, determine the future applications of these materials. The mechanisms involved on the origin of such induced magnetic anisotropy showed significant differences between Fe-rich and Co-rich amorphous alloys. This work provides a comparative study of the coercive field and induced magnetic anisotropy in Fe-rich and Co-rich (Finemet) amorphous alloys treated by stress and/or field. r 2005 Elsevier B.V. All rights reserved. PACS: 75.30.G; 75.60.Nt Keywords: Amorphous ferromagnetic alloys; Stress and/or field annealing; Coercive field; Induced magnetic anisotropy 1. Introduction The use of amorphous ferromagnetic alloys enables considerable improvement of some devices that use soft magnetic materials. Particularly, good improvements can be obtained for devices operating at high-frequency regime. Because of this fact, present efforts on the improvement of the properties of amorphous ferromagnets are directed towards the achievement of materials with good frequency characteristics in the selection of suita- ble compositions, various post-preparation treat- ments, (thermal, etc) are required. In particular, the controlled formation of nanocrystals and scratching of surfaces have been found to improve significantly the properties of those materials specially in the region of sufficiently high frequen- cies. Although the effects of these treatments on ARTICLE IN PRESS www.elsevier.com/locate/jmmm 0304-8853/$ - see front matter r 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.jmmm.2005.03.041 à Corresponding author. Tel.: +34 943 015407; fax: +34 943 017230. E-mail address: wapgoesj@sc.ehu.es (J. Gonza´lez).