Spin transfer torque magnetic random access memory (STTMRAM) having graded synthetic free layer

摘要

A spin transfer torque memory random access memory (STTMRAM) element is capable of switching states when electrical current is applied thereto for storing data and includes the following layers. An anti-ferromagnetic layer, a fixed layer formed on top of the anti-ferromagnetic layer, a barrier layer formed on top of the second magnetic layer of the fixed layer, and a free layer including a first magnetic layer formed on top of the barrier layer, a second magnetic layer formed on top of the first magnetic layer, a nonmagnetic insulating layer formed on top of the second magnetic layer and a third magnetic layer formed on top of the non-magnetic insulating layer. A capping layer is formed on top of the non-magnetic insulating layer.

主权项

1. A spin transfer torque magnetic random access memory (STTMRAM) element comprising:
an anti-ferromagnetic layer; a magnetic fixed layer structure formed on top of said anti-ferromagnetic layer, said magnetic fixed layer comprising two invariable magnetic sublayers having opposite magnetization directions with an anti-ferromagnetic coupling sublayer interposed therebetween; a magnetic free layer separated from said magnetic fixed layer by an insulating tunnel barrier layer, said magnetic free layer comprising: a first variable magnetic sublayer formed on top of said insulating tunnel barrier layer; a second variable magnetic sublayer formed on top of said first magnetic sublayer; and a third variable magnetic sublayer separated from said second variable magnetic sublayer by a coupling sublayer, said coupling sublayer including at least a non-magnetic insulating layer and a non-magnetic conductive layer, wherein said first and second variable magnetic sublayers have substantially the same magnetization direction that is substantially opposite to the magnetization direction of said third variable magnetic sublayer; and a capping layer formed on top of said third variable magnetic layer of said magnetic free layer, wherein said second variable magnetic sublayer of said magnetic free layer has a lower saturation magnetization than said first and third variable magnetic sublayers of said magnetic free layer.