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The Effect of Stress Induced Anisotropy in Patterned FeCo Thin Film Structures



Wonpil Yu, J A. Bain, Willard C. Uhlig, John Unguris


The usage of high moment FeCo alloys in magnetic recording heads can result in stress induced anisotropy due to the high magnetostriction constants of FeCo alloys with 30% to 50% Co. In this work, 1um thick FeCo (65% Fe, 35% Co) sheet films with a Cu underlayer with -320 MPa of compressive stress and 1um thick FeCo/Permalloy multilayer films with 600 MPa of stress were patterned into 5um x 20um structures.Domain analysis shows that the domain structure of the patterned elements was influenced by the presence of stress induced anisotropy. Figure 1a shows that closure domains were seen in the FeCo/Permalloy multilayer structures, while the compressive FeCo structures in Figure 1b show magnetic domains oriented parallel to the width of the structures. The stress anisotropy in the compressive FeCo patterned elements resulted in a high effective anisotropy field that rotated the easy axis 90 degrees away from the anticipated easy axis along the length of the structure. Theoretical calculations of the effect of stress anisotropy on the total energy of domain configurations for 5x20 um patterned structures indicate tensile stressed films and structures reinforce closure domains, while films with compressive stress less than -50 MPa result in a rotation of the easy axis. Through domain structure calculations and stress analysis in patterned structures, it is possible to estimate the effect of stress anisotropy in patterned thin films. a) Magnetic domains in a 5x20um structure of 1um FeCo with -320 MPa of stress b) Magnetic domains in a 5x20um structure of 1um FeCo/Permalloy with 600 MPa of stress.
Proceedings Title
Proceedings | 50th
99 No 8
Conference Dates
October 30-November 3, 2005
Conference Location
Conference Title
Magnetism and Magnetic Materials Conference


FeCo, magnetic domains, NiFe, patterned films, stress


Yu, W. , Bain, J. , Uhlig, W. and Unguris, J. (2006), The Effect of Stress Induced Anisotropy in Patterned FeCo Thin Film Structures, Proceedings | 50th, Undefined (Accessed May 20, 2024)


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Created March 31, 2006, Updated October 12, 2021