Underlayer for high amplitude spin valve sensors

A method of fabricating a spin valve (SV) sensor comprising:

• depositing an underlayer comprising NiFeX;
• depositing an upper layer adjacent the underlayer, the upper layer comprising a material selected from the group consisting of NiFe and CoFe for increasing a GMR ratio associated with the SV sensor;
• depositing a pinning layer adjacent the upper layer;
• depositing a pinned layer adjacent the pinning layer, the pinned layer having a pinned layer magnetization;
• depositing a spacer layer adjacent the pinned layer;
• and
• depositing a free layer adjacent the pinned layer, the free layer having a free layer magnetization perpendicular to the pinned layer magnetization in the absence of an external field.

A spin valve (SV) sensor comprising:

• a pinned layer having a pinned layer magnetization;
• a free layer disposed adjacent the pinned layer, the free layer having a free layer magnetization perpendicular to the pinned layer magnetization in the absence of an external field;
• a spacer layer disposed between the free layer and the pinned layer;
• a pinning layer disposed adjacent the pinned layer for fixing the pinned layer magnetization, the pinning layer comprising PtMn;
• an underlayer disposed adjacent the pinning layer, the underlayer comprising NiFeCr;and
• an upper layer disposed adjacent the underlayer and the pinning layer, the upper layer comprising CoFe for increasing a GMR ratio associated with the SV sensor.

A spin valve (SV) sensor comprising:

• a pinned layer having a pinned layer magnetization;
• a free layer disposed adjacent the pinned layer, the free layer having a free layer magnetization perpendicular to the pinned layer magnetization in the absence of an external field;
• a spacer layer disposed between the free layer and the pinned layer;
• a pinning layer disposed adjacent the pinned layer for fixing the pinned layer magnetization, the pinning layer comprising PtMn;
• an underlayer disposed adjacent the pinning layer, the underlayer comprising NiFeCr;and
• an upper layer disposed adjacent the underlayer and the pinning layer, the upper layer comprising NiFe for increasing a GMR ratio associated with the SV sensor.

A spin valve (SV) sensor comprising:

• a pinned layer having a pinned layer magnetization;
• a free layer disposed adjacent the pinned layer, the free layer having a free layer magnetization perpendicular to the pinned layer magnetization in the absence of an external field;
• a pinning layer disposed adjacent the pinned layer for fixing the pinned layer magnetization;
• an underlayer disposed adjacent the pinning layer, the underlayer comprising NiFeCr;
• and
• an upper layer disposed adjacent the underlayer and the pinning layer, the upper layer comprising a material selected from the group consisting of NiFe and CoFe for increasing a GMR ratio associated with the SV sensor;
• wherein the upper layer has a thickness between 4 A and 20 A.

A spin valve (SV) sensor comprising:

• pinned layer having a pinned layer magnetization, the pinned layer comprising a Ru layer with a first CoFe layer disposed adjacent a first side of the Ru layer and a second CoFe layer disposed adjacent a second side of the Ru layer;
• a free layer disposed adjacent the pinned layer, the free layer having a free layer magnetization perpendicular to the pinned layer magnetization in the absence of an external field, the free layer comprising a NiFe layer with a third CoFe layer disposed adjacent thereto;
• a spacer layer disposed between the free layer and the pinned layer;
• a pinning layer disposed adjacent the pinned layer for fixing the pinned layer magnetization, the pinning layer comprising PtMn;
• an underlayer disposed adjacent the pinning layer, the underlayer comprising NiFeCr;
• and
• an upper layer disposed adjacent the underlayer and the pinning layer, the upper layer comprising a material selected from the group consisting of NiFe and CoFe for increasing a GMR ratio associated with the SV sensor.

A disk drive system, comprising:

• a magnetic recording disk;
• a spin valve (SV) sensor including:
• a pinned layer having a pinned layer magnetization;
• a free layer disposed adjacent the pinned layer, the free layer having a free layer magnetization perpendicular to the pinned layer magnetization in the absence of an external field,
• spacer layer disposed between the free layer and the pinned layer,
• a pinning layer disposed adjacent the pinned layer for fixing the pinned layer magnetization,
• an underlayer disposed adjacent the pinning layer, the underlayer comprising NiFeX, and
• an upper layer disposed adjacent the underlayer and the pinning layer, the upper layer comprising a material selected from the group consisting of NiFe and CoFe for increasing a GMR ratio associated with the SV sensor;
• an actuator for moving the SV sensor across the magnetic recording disk so the SV sensor may access different regions of magnetically recorded data on the magnetic recording disk;
• and
• a controller electrically coupled to the SV sensor for detecting changes in resistance of the SV sensor.