Current perpendicular to plane magnetoresistive head having suppressed spin torque noise
View Patent ↗Embodiments of the present invention aim suppress the generation of spin torque noise in a current perpendicular to plane magnetoresistive head. According to one embodiment, when sensing current is applied to a current perpendicular to plane magnetoresistive head from a free layer toward a first pinned layer, a configuration wherein the relative angle between the magnetization of a second pinned layer and the magnetization of the free layer is in the range of 70 to 80 degrees is used. Further, when sensing current is applied to a current perpendicular to plane magnetoresistive head from a first pinned layer toward a free layer, a configuration wherein the relative angle between the magnetization of a second pinned layer and the magnetization of the free layer is in the range of 100 to 110 degrees is used.
1. A current perpendicular to plane magnetoresistive head characterized in that: the head has a structure formed by an antiferromagnetic layer, and by laminating a first pinned layer, an antiparallel coupling layer, a second pinned layer, a nonmagnetic intermediate layer, and a free layer in sequence, and wherein no additional pinned layer is formed beyond the free layer in sequence; sensing current flows from the free layer toward the first pinned layer; and the relative angle of magnetization between the second pinned layer and the free layer is in the range of 70 to 80 degrees in the state where a magnetic field to be sensed is not applied, and wherein spin torque noise is suppressed based on the relative angle and the direction of the sensing current.
2. The current perpendicular to plane magnetoresistive head according to claim 1 , characterized in that, when the product of the thickness and the saturation magnetization of the first pinned layer is defined as M 1 and the product of the thickness and the saturation magnetization of the second pinned layer is defined as M 2 , M 1 is larger than M 2 .
3. The current perpendicular to plane magnetoresistive head according to claim 1 , characterized in that the magnetization of the second pinned layer leans by 10 to 20 degrees from the direction of sensor height.
4. A current perpendicular to plane magnetoresistive head characterized in that: the head has a structure formed by an antiferromagnetic layer, and by laminating a first pinned layer, an antiparallel coupling layer, a second pinned layer, a nonmagnetic intermediate layer, and a free layer in sequence, and wherein no additional pinned layer is formed beyond the free layer in sequence; sensing current flows from the first pinned layer toward the free layer; and the relative angle of magnetization between the second pinned layer and the free layer is in the range of 100 to 110 degrees in the state where a magnetic field to be sensed is not applied, and wherein spin torque noise is suppressed based on the relative angle and the direction of the sensing current.
5. The current perpendicular to plane magnetoresistive head according to claim 4 , characterized in that, when the product of the thickness and the saturation magnetization of the first pinned layer is defined as M 1 and the product of the thickness and the saturation magnetization of the second pinned layer is defined as M 2 , M 2 is larger than M 1 .
6. The current perpendicular to plane magnetoresistive head according to claim 4 , characterized in that the magnetization of the second pinned layer leans by 10 to 20 degrees from the direction of sensor height.
7. A magnetoresistive head having a current perpendicular to plane magnetoresistive element formed by an antiferromagnetic layer, and by laminating a first pinned layer, an antiparallel coupling layer, a second pinned layer, a nonmagnetic intermediate layer, and a free layer in sequence, and wherein no additional pinned layer is formed beyond the free layer in sequence, wherein sensing current is configured to flow between a first electrode disposed on the side of the free layer and a second electrode disposed on the side of the first pinned layer, the head being characterized in that: the sensing current is configured to flow in one of the following directions: (a) from the free layer toward the first pinned layer such that the asymmetry of a signal waveform is in the range of less than 0% to −10% or greater than 0% to +20%; or (b) from the first pinned layer toward the free layer such that the asymmetry of the signal waveform is in the range of −20% to −10%; and wherein spin torque noise is suppressed based on the signal waveform asymmetry.
8. A magnetoresistive head having a current perpendicular to plane magnetoresistive element formed by an antiferromagnetic layer, and by laminating a first pinned layer, an antiparallel coupling layer, a second pinned layer, a nonmagnetic intermediate layer, and a free layer in sequence, and wherein no additional pinned layer is formed beyond the free layer in sequence, wherein sensing current is configured to flow between a first electrode disposed on the side of the free layer and a second electrode disposed on the side of the first pinned layer, the head being characterized in that: the sensing current is configured to flow in one of the following directions: (a) from the first pinned layer toward the free layer such that the asymmetry of a signal waveform is in the range of less than 0% to −20% or greater than 0% to +10%; or (b) from the free layer toward the first pinned layer such that the asymmetry of the signal waveform is in the range of +10% to +20%; and wherein spin torque noise is suppressed based on the signal waveform asymmetry.