Co/Ni multilayers with improved out-of-plane anisotropy for magnetic device applications

摘要

A MTJ for a spintronic device includes a thin seed layer that enhances perpendicular magnetic anisotropy (PMA) in an overlying laminated layer with a (Co/Ni)n composition or the like where n is from 2 to 30. The seed layer is preferably NiCr, NiFeCr, Hf, or a composite thereof with a thickness from 10 to 100 Angstroms. Furthermore, a magnetic layer such as CoFeB may be formed between the laminated layer and a tunnel barrier layer to serve as a transitional layer between a (111) laminate and (100) MgO tunnel barrier. There may be a Ta insertion layer between the CoFeB layer and laminated layer to promote (100) crystallization in the CoFeB layer. The laminated layer may be used as a reference layer in a MTJ. Annealing between 300° C. and 400° C. may be used to further enhance PMA in the laminated layer.

主权项

1. A magnetic tunnel junction (MTJ), comprising:
(a) a seed layer formed on a substrate and comprising one or more of Hf, NiFeCr, and NiCr that enhances PMA in an overlying laminated layer; (b) a composite reference layer comprising the laminated layer that contacts a top surface of the seed layer, the laminated layer has intrinsic PMA and comprises a multilayer stack that inclpdes two magnetic elements, a magnetic element and alloy, or two alloys represented by (A1/A2)n or (A1/C/A2) where A1 is a first metal or alloy, A2 is a second metal or alloy, C is a non-magnetic spacer, and n is the number of laminates in the laminated layer, the composite reference layer also includes an upper magnetic layer that has PMA with a magnetization in the same direction as the PMA in the laminated layer; (c) a tunnel barrier layer contacting a top surface of the upper magnetic layer; (d) a free layer formed on the tunnel barrier layer; and (e) a capping layer as the uppermost layer in the MTJ.