THE TRADE-OFF BETWEEN LARGE MAGNETORESISTANCE AND SMALL COERCIVITY INSYMMETRICAL SPIN VALVES

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 t hat exhibit smaller coercivities than pure Co for the center or ''valv e'' film but which retain much of the giant magnetoresistance associat ed with a pure Co film. The materials investigated include Co95Fe5, Co 90Fe10, Ni80Fe20, Co86Fe10.5Ni3.5, and Co85B15. It appears that each o f these alloys scatters electrons more strongly than does pure Co as t hey cross the center film. This scattering degrades the dual spin-valv e 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. (C) 1996 American Institute of Physics.