Co/Ni multilayers with improved out-of-plane anisotropy for magnetic device applications
View Patent ↗A MTJ for a spintronic device is disclosed and 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, dipole layer, or free layer in a MTJ. Annealing between 300° C. and 400° C. may be used to further enhance PMA in the laminated layer.
1. A magnetic element, comprising:
(a) a seed layer comprising one or more of Hf, NiCr, and NiFeCr that enhances perpendicular magnetic anisotropy (PMA) in an overlying laminated layer; and
(b) the laminated layer having intrinsic PMA and comprising an alloy with a L10 structure of the form MT where M is Rh, Pd, Pt, Ir, or alloy thereof, and T is Fe, Co, Ni, or alloy thereof.
2. The magnetic element of claim 1 wherein the seed layer and laminated layer are formed in a magnetic tunnel junction (MTJ) having a seed layer/reference layer/tunnel barrier/free layer configuration, the laminated layer is part of the reference layer, and the reference layer further comprises a magnetic layer formed between the laminated layer and the tunnel barrier to increase the magnetoresistive (MR) ratio in the magnetic element, the magnetic layer interfaces with the tunnel barrier and has PMA with a magnetic moment in the same direction as the PMA in the laminated layer.
3. The magnetic element of claim 1 wherein the seed layer and laminated layer are formed in a MTJ having a reference layer/tunnel barrier/free layer/spacer/seed layer/dipole layer configuration and the laminated layer is the dipole layer.
4. The magnetic element of claim 1 wherein the seed layer and laminated layer are formed in a MTJ having a seed layer/composite free layer/tunnel barrier/reference layer configuration and the laminated layer is part of the composite free layer, and the composite free layer further comprises a magnetic layer formed between the laminated layer and the tunnel barrier to increase the magnetoresistive (MR) ratio in the magnetic element, the magnetic layer interfaces with the tunnel barrier and has PMA with a magnetic moment in the same direction as the PMA in the laminated layer.
5. The magnetic element of claim 1 wherein the laminated layer is doped with boron up to about 40 atomic %.