The Trade-Off Between Large Magnetoresistance and Small Coercivity in Symmetric Spin Valves

W.F. Egelhoff, Jr., P.J. Chen, C.J. Powell, M.D. Stiles, R.D. McMichael, C.-L. Lin, J.M. Sivertsen, J.H. Judy, K. Takano, and A.E. Berkowitz

Journal of Applied Physics 79(11), 8603-8605 (1996)

Abstract:

We have investigated the use of various alloys as substitutes for pure Co in the center film of symmetric spin valves of the type NiO/Co/Cu/Co/Cu/Co/NiO. The aim of this work is to identify magnetic materials that exhibit smaller coercivities than pur Co for the center or "valve" film but which retain much of the giant magnetoresistance associated with a pure Co film. The materials investigated include Co₉₅Fe₅, Co₉₀Fe₁₀, Ni₈₀Fe₂₀, Co₈₆Fe_10.5Ni_3.5, and Co₈₅B₁₅. It appears that each of these alloys scatters electrons more strongly than does pure Co as they cross the center film. This scattering degrades the dual spin-valve effect, which is the primary advantage of the symmetric spin valve. As a result, a tradeoff exists between large GMR and small coercivity when using these materials.

Keywords: coercivity; giant magnetoresistance; superlattices

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