Current-perpendicular-to-the-plane (CPP) magnetoresistive (MR) sensor structure with stacked sensors for minimization of the effect of head skew

1. A two-dimensional magnetic recording (TDMR) disk drive comprising:

a rotatable magnetic recording disk having a plurality of concentric data tracks having a track pitch TP, the disk having an inside diameter (ID) region, a mid-diameter (MD) region and an outside (OD) diameter region;

a multi-sensor read head for generating readback signals from the data tracks;

a rotary actuator for moving the head in a generally arcuate path across the data tracks, wherein the head has a skew angle (A) relative to an along-the-track direction as a function of radial position;

wherein the multi-sensor read head comprises:

a head carrier having a surface for facing the disk and a trailing surface generally orthogonal to the disk-facing surface;

a bottom magnetic shield on the trailing surface;

a first read sensor on the bottom magnetic shield for reading a target track;

a first magnetic shield on the first read sensor;

a second read sensor on the first magnetic shield for reading a track adjacent to the target track when θ is zero;

a second magnetic shield on the second read sensor;

a third read sensor on the second magnetic shield and aligned laterally with the first read sensor in a direction substantially parallel to the trailing surface, the third read sensor being spaced a distance D from the first read head in a direction substantially orthogonal to the trailing surface, wherein D is related to TP and a maximum skew angle (θ m ); and

a top magnetic shield on the third read head; and

circuitry responsive to the radial position of the multi-sensor read head for selecting two of the sensors as active sensors for providing readback signals, the circuitry including switch means for selecting the first and second sensors as the active sensors when the head is located in the MD region, and for selecting the first and third sensors when the head is located in the ID and OD regions.

2. The disk drive of claim 1 wherein the second read sensor is spaced a distance D/2 from the first read sensor in a direction substantially orthogonal to the trailing surface.

3. The disk drive of claim 1 wherein D is substantially equal to (TP)/sin θ m .

4. The disk drive of claim 1 wherein D is substantially equal to (TP−δ)/sin θ m , wherein δ is a predetermined tolerance in the lateral alignment of the third read sensor relative to the first read sensor.

5. The disk drive of claim 1 wherein the three sensors have substantially the same lateral width in a direction parallel to the trailing surface.

6. The disk drive of claim 1 wherein at least one of the three sensors has a lateral width greater than TP in a direction parallel to the trailing surface.

7. A system for providing readback signals from adjacent data tracks in a two-dimensional magnetic recording (TDMR) disk drive having a rotary actuator with a maximum skew angle (θ m ) and a disk having an inside diameter (ID) region, a mid-diameter (MD) region, an outside (OD) diameter region, and a track pitch (TP), the system comprising:

a multi-sensor read head comprising:

a head carrier having a surface for facing the disk and a trailing surface generally orthogonal to the disk-facing surface;

a bottom magnetic shield on the trailing surface;

a first read sensor on the bottom magnetic shield;

a first magnetic shield on the first read sensor;

a second read sensor on the first magnetic shield and spaced laterally a distance X from the first read sensor in a direction substantially parallel to the trailing surface, wherein X is related to TP;

a second magnetic shield on the second read sensor;

a third read sensor on the second magnetic shield and aligned laterally with the first read sensor in a direction substantially parallel to the trailing surface, the third read sensor being spaced a distance D from the first read sensor in a direction substantially orthogonal to the trailing surface, wherein D is related to θ m ; and

a top magnetic shield on the third read sensor; and

a preamplifier connected to the multi-sensor read head for simultaneously providing a readback signal from a target track and a readback signal from a track adjacent to the target track, the preamplifier including circuitry for selecting the first read sensor to provide the readback signal from the target track and the second read sensor to provide the readback signal from an adjacent track when the multi-sensor read head is located in the MD region, and for selecting the first read sensor to provide the readback signal from the target track and the third read sensor to provide the readback signal from an adjacent track when the multi-sensor read head is located in the ID and OD regions.

8. The system of claim 7 wherein the second read sensor is spaced a distance D/2 from the first read sensor in a direction substantially orthogonal to the trailing surface.

9. The system of claim 7 wherein D is substantially equal to (TP)/sin θ m .

10. The system of claim 7 wherein D is substantially equal to (TP−δ)/sin θ m , wherein δ is a predetermined tolerance in the lateral alignment of the third read sensor relative to the first read sensor.

11. The system of claim 7 wherein the three sensors have substantially the same lateral width in a direction parallel to the trailing surface.

12. The system of claim 7 wherein at least one of the three sensors has a lateral width greater than TP in a direction parallel to the trailing surface.