Adjustable spin torque in magnetic tunnel junctions with two fixed layers

Fuchs, G. D.; Krivorotov, I. N.; Braganca, P. M.; Emley, N. C.; Garcia, A. G. F.; Ralph, D. C.; Buhrman, R. A.
April 2005
Applied Physics Letters;4/11/2005, Vol. 86 Issue 15, p152509
Academic Journal
We have fabricated nanoscale magnetic tunnel junctions (MTJs) with an additional fixed magnetic layer added above the magnetic free layer of a standard MTJ structure. This acts as a second source of spin-polarized electrons that, depending on the relative alignment of the two fixed layers, either augments or diminishes the net spin torque exerted on the free layer. The compound structure allows a quantitative comparison of spin torque from tunneling electrons and from electrons passing through metallic spacer layers, as well as analysis of Joule self-heating effects. This has significance for current-switched magnetic random access memory, where spin torque is exploited and, for magnetic sensing, where it is detrimental.


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