Localized magnetic modification of permalloy using Cr+ ion implantation

• Published in: Journal of physics. D, Applied physics Applied physics, 2003-11, Vol.36 (21), p.2601-2604
• Main Authors: Folks, L, Fontana, R E, Gurney, B A, Childress, J R, Maat, S, Katine, J A, Baglin, J E E, Kellock, A J
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Magnetic properties and materials; Magnetic properties of monolayers and thin films; Magnetic properties of surface, thin films and multilayers; Magnetic recording materials; Metals. Metallurgy; Physics; Studies of specific magnetic materials
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/36/21/001

Doping ferromagnetic nickel-iron alloys with chromium causes the Curie temperature to be reduced. We have demonstrated that solid state solutions of Ni-Fe-Cr can be formed by implanting Cr ions into ferromagnetic NiFe alloy films, thus creating paramagnetic films. We find that the magnetic moment and coercivity decrease steadily with Cr(+) dose, reaching zero at room temperature with the onset of paramagnetism. Using Cr(+) implantation in conjunction with a lithographic mask we have patterned continuous Ni(80)Fe(20) films into separate regions that are ferromagnetic and paramagnetic at room temperature. This magnetic patterning process may have applications for the manufacture of magnetic write heads, such as for the notching process used to constrain the stray field from the write gap.