Read sensor stabilized by bidirectional anisotropy

A method of forming a longitudinal flux-closure structure for a read sensor, the method comprising:

• depositing an antiferromagnetic pinning layer;
• depositing a ferromagnetic bias layer on top of the antiferromagnetic pinning layer;
• depositing a nonmagnetic spacer layer on top of the ferromagnetic bias layer;
• and
• depositing a ferromagnetic sense layer on top of the nonmagnetic spacer layer;
• wherein a magnetization of the ferromagnetic bias layer is pinned in a longitudinal direction by the antiferromagnetic pinning layer, and the longitudinal magnetization of the ferromagnetic bias layer biases the ferromagnetic sense layer across the nonmagnetic spacer layer in the longitudinal direction;
• wherein exchange coupling between the antiferromagnetic pinning layer and the ferromagnetic bias layer is stronger than antiparallel coupling across the nonmagnetic spacer layer between the ferromagnetic bias layer and the ferromagnetic sense layer.

A read sensor, comprising:

• at least one nonmagnetic seed layer;
• a first antiferromagnetic pinning layer adjacent to the at least one nonmagnetic seed layer;
• a ferromagnetic bias layer adjacent to the first antiferromagnetic pinning layer;
• a first nonmagnetic spacer layer adjacent to the ferromagnetic bias layer;
• a ferromagnetic sense layer adjacent to the first nonmagnetic spacer layer;
• wherein a magnetization of the ferromagnetic bias layer is pinned in a backward longitudinal direction by the first antiferromagnetic pinning layer, and the longitudinal magnetization of the ferromagnetic bias layer biases the ferromagnetic sense layer across the first nonmagnetic spacer layer in a forward longitudinal direction;
• wherein antiferromagnetic/ferromagnetic exchange coupling between the first antiferromagnetic pinning layer and the ferromagnetic bias layer induces a unidirectional anisotropy and ferromagnetic/ferromagnetic antiparallel coupling across the first nonmagnetic spacer layer induces a bidirectional anisotropy, wherein the unidirectional anisotropy is larger than the bidirectional anisotropy;
• a GMR spacer or TMR barrier layer adjacent to the ferromagnetic sense layer;
• a ferromagnetic reference layer adjacent to the GMR spacer or TMR barrier layer;
• a second nonmagnetic spacer layer adjacent to the ferromagnetic reference layer;
• a ferromagnetic keeper layer adjacent to the second nonmagnetic spacer layer;
• a second antiferromagnetic pinning layer adjacent to the ferromagnetic keeper layer;
• and
• a nonmagnetic cap layer adjacent to the second antiferromagnetic pinning layer.

A method of fabricating a read sensor, the method comprising:

• depositing at least one nonmagnetic seed layer;
• depositing a first antiferromagnetic pinning layer on top of the at least one nonmagnetic seed layer;
• depositing a ferromagnetic bias layer on top of the first antiferromagnetic pinning layer;
• depositing a first nonmagnetic spacer layer on top of the ferromagnetic bias layer;
• depositing a ferromagnetic sense layer on top of the nonmagnetic spacer layer;
• wherein a magnetization of the ferromagnetic bias layer is pinned in a backward longitudinal direction by the first antiferromagnetic pinning layer, and the longitudinal magnetization of the ferromagnetic bias layer biases the ferromagnetic sense layer across the first nonmagnetic spacer layer in a forward longitudinal direction;
• wherein antiferromagnetic/ferromagnetic exchange coupling between the first antiferromagnetic pinning layer and the ferromagnetic bias layer induces a unidirectional anisotropy and ferromagnetic/ferromagnetic antiparallel coupling across the first nonmagnetic spacer layer induces a bidirectional anisotropy, wherein the unidirectional anisotropy is larger than the bidirectional anisotropy;
• depositing a GMR spacer or TMR barrier layer on top of the ferromagnetic sense layer;
• depositing a ferromagnetic reference layer on top of the GMR spacer or TMR barrier layer;
• depositing a second nonmagnetic spacer layer on top of the ferromagnetic reference layer;
• depositing a ferromagnetic keeper layer on top of the second nonmagnetic spacer layer;
• depositing a second antiferromagnetic pinning layer on top of the ferromagnetic keeper layer;
• and
• depositing a nonmagnetic cap layer on top of the second antiferromagnetic pinning layer.