Method and system for providing magnetic junctions having improved polarization enhancement and reference layers

A magnetic junction for use in a magnetic device comprising:

• a free layer having a free layer magnetic moment perpendicular-to-plane;
• a crystalline MgO layer;
• a reference stack including a high perpendicular magnetic anisotropy (PMA) layer and a graded polarization enhancement layer (PEL), the crystalline MgO layer residing between the graded PEL and the free layer, the graded PEL being adjacent to and magnetically coupled with the high PMA layer, the graded PEL being between the crystalline MgO layer and the high PMA layer, the high PMA layer having a reference layer magnetic moment perpendicular-to-plane and a first spin polarization, the graded PEL layer being adjacent to and magnetically coupled with the high PMA layer, the graded PEL including a plurality of magnetic layers and a plurality of Ta insertion layers, at least a layer of the plurality of magnetic layers having a second spin polarization greater than the first spin polarization and including CoFeB having not more than twenty atomic percent B, each of the plurality of Ta insertion layers having a thickness of less than three Angstroms, at least the layer being adjacent to the crystalline MgO layer, a sum of the thickness of each of the plurality Ta insertion layers being sufficient for diffusion blocking between the high PMA layer and the crystalline MgO layer and being at least four Angstroms, the thickness of each of the plurality of Ta insertion layers being insufficient for the diffusion blocking between the reference layer and the crystalline MgO layer;
• wherein the magnetic junction is configured such that the free layer is switchable between a plurality of stable magnetic states when a write current is passed through the magnetic junction.

A magnetic memory comprising:

• a plurality of magnetic storage cells, each of the plurality of magnetic storage cells including at least one magnetic junction, the at least one magnetic junction including a free layer, a nonmagnetic spacer layer and a reference stack, the free layer having a free layer magnetic moment perpendicular-to-plane, the nonmagnetic spacer layer having a first crystalline orientation, the nonmagnetic spacer layer being between the reference stack and the free layer, the reference stack including a high perpendicular magnetic anisotropy (PMA) layer and a graded polarization enhancement layer (PEL), the graded PEL residing between the high PMA layer and the nonmagnetic spacer layer, the high PMA layer having a magnetic moment perpendicular-to-plane, a second crystalline orientation and a first spin polarization, the graded PEL being adjacent to and magnetically coupled with the high PMA layer, the graded PEL including a plurality of magnetic layers and a plurality of nonmagnetic insertion layers, at least a portion of the PEL having a second spin polarization greater than the first spin polarization and being adjacent to the nonmagnetic spacer layer, the plurality of nonmagnetic insertion layers being configured such that the plurality of magnetic layers are ferromagnetically coupled and such that the first crystalline orientation is decoupled from the second crystalline orientation, the magnetic junction being configured such that the free layer is switchable between a plurality of stable magnetic states when a write current is passed through the magnetic junction, each of the plurality of nonmagnetic insertion layers having a thickness, the thickness of each of the plurality of nonmagnetic insertion layers being insufficient for the first crystalline orientation to be decoupled from the second crystalline orientation in the absence of a remaining portion of the plurality of nonmagnetic insertion layers;
• and
• a plurality of bit lines coupled with the plurality of magnetic storage cells.

A method for providing a magnetic junction for use in a magnetic device comprising:

• providing a free layer having a free layer magnetic moment perpendicular-to-plane;
• providing a nonmagnetic spacer layer having a first crystalline orientation,
• providing a reference stack, the step or providing the reference stack including the steps of
• providing a high perpendicular magnetic anisotropy (PMA) layer, the high PMA layer having a magnetic moment perpendicular-to-plane, a second crystalline orientation and a first spin polarization;
• and
• providing a graded polarization enhancement layer (PEL), the nonmagnetic spacer layer residing between the graded PEL and the free layer, the graded PEL residing between the high PMA layer and the nonmagnetic spacer layer, the graded PEL being adjacent to and magnetically coupled with the high PMA layer, the graded PEL including a plurality of magnetic layers and a plurality of nonmagnetic insertion layers, at least a portion of the PEL having a second spin polarization greater than the first spin polarization and being adjacent to the nonmagnetic spacer layer, the plurality of nonmagnetic insertion layers being configured such that the plurality of magnetic layers are ferromagnetically coupled and such that the first crystalline orientation is decoupled from the second crystalline orientation, each of the plurality of nonmagnetic insertion layers having a thickness, the thickness of each of the plurality of nonmagnetic insertion layers being insufficient for the first crystalline orientation to be decoupled from the second crystalline orientation in the absence of a remaining portion of the plurality of nonmagnetic insertion layers;
• wherein the magnetic junction is configured such that the free layer is switchable between a plurality of stable magnetic states when a write current is passed through the magnetic junction.