CPP-GMR sensor with non-orthogonal free and reference layer magnetization orientation

A CPP magnetic head having an air bearing surface (ABS), comprising:

• a ferromagnetic pinned layer;
• an antiparallel coupling layer above the pinned layer;
• a ferromagnetic reference layer above the antiparallel coupling layer, the reference layer being antiparallel coupled to the pinned layer;
• a spacer layer above the reference layer;
• a ferromagnetic free layer above the spacer layer, a longitudinal axis being defined as the intersection of the plane of deposition of the free layer and the plane of the ABS;
• wherein the free layer has a bias-point magnetization orientation nominally in the film plane in a first direction at an angle θfb with respect to said longitudinal axis;
• and
• wherein the reference layer has a bias-point magnetization orientation θrb nominally in the film plane in a second direction at an angle that is not orthogonal to the first direction.

A dual CPP magnetic head having an air bearing surface (ABS), comprising:

• a ferromagnetic free layer film having bias-point magnetization orientation nominally in the film plane in a first direction described by angle θfb with respect to a longitudinal axis defined by the intersection of the free layer film plane and a plane of the ABS;
• a first ferromagnetic reference layer film having a magnetization orientation nominally in a plane of the film thereof in a second direction described by angle θr1 that is not orthogonal to the first direction;
• a first spacer layer between the free and first reference layers;
• a second reference layer positioned on an opposite side of the free layer than the first reference layer, the second reference layer having a magnetization orientation nominally in a plane of the film thereof in a third direction normally oriented in a third direction described by angle θr1 that is not orthogonal to the first direction;
• and
• a second spacer layer between the free and second reference layers.

A magnetic head, comprising:

• a free layer;
• a reference layer;
• a pinned layer
• a coupling layer between the pinned and reference layers;
• and
• a spacer layer between the free and reference layers;
• wherein the reference layer has a magnetization direction fixed by the pinned layer through a coupling layer,
• wherein the antiferromagnetic layer fixes the direction of magnetization of the pinned layer,
• wherein the direction of magnetization of the free layer is oriented relative to the direction of magnetization of the reference layer as determined by a parameter Q, Q being the scalar product of the unit magnetization vector of the free layer with the unit magnetization vector of the reference layer,
• wherein a value of Q and the magnitude and polarity of the bias current are such that the sensor is not subject to spin-torque induced instability during operation.