Method and apparatus for providing magnetostriction control in a freelayer of a magnetic memory device
First Claim
1. A method for controlling magnetostriction in a free layer of a magnetic memory device, comprising:
- forming a pinned layer;
forming a separation layer over the pinned layer; and
forming a bilayer, composite free layer, the forming the bilayer, composite free layer includes;
forming a first free layer, the first free layer comprising a CoFe alloy; and
forming a second free layer, the second free layer comprising a NiFe alloy,wherein the forming the first free layer of CoFe alloy and the forming of the second free layer of NiFe alloy further comprises forming the first free layer of CoFe alloy with a predetermined first thickness and forming the second free layer of NiFe with a predetermined second thickness, wherein the ratio of the predetermined first thickness to the predetermined second thickness is selected to provide a predetermined magnetostriction and wherein at least one of the CoFe alloy and NiFe alloy includes an addition of at least one element of B, P, Si, Nb, Zr, Hf, Ta and Ti, the ratio of the first thickness and second thickness being selected to provide a desired magnetostriction and the addition of at least one element of B, P, Si, Nb, Zr, Hf, Ta and Ti being controlled to maintain a substantially constant sensor resistance while adjusting the ratio of the first thickness and second thickness to provide a desired magnetostriction.
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Accused Products
Abstract
A method and apparatus for providing magnetostriction control in a synthetic free layer of a magnetic memory device is disclosed. A first free layer of CoFe alloy has a first thickness. A second free layer of NiFe alloy has a second thickness. At least one of the CoFe alloy and NiFe alloy includes at least one of B, P, Si, Nb, Zr, Hf, Ta and Ti. The relative thicknesses of the first and second free layer are modified to obtain a desired magnetostriction without a change in the magenetoristance ratio, ΔR/R. The synthetic free layer may also be configured to have a net magnetic moment. A sensor may be a current-in-plane or a current-perpendicular-to-the-plane sensor. The sensor also may be configured to be a GMR sensor or a TMR sensor.
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Citations
21 Claims
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1. A method for controlling magnetostriction in a free layer of a magnetic memory device, comprising:
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forming a pinned layer; forming a separation layer over the pinned layer; and forming a bilayer, composite free layer, the forming the bilayer, composite free layer includes; forming a first free layer, the first free layer comprising a CoFe alloy; and forming a second free layer, the second free layer comprising a NiFe alloy, wherein the forming the first free layer of CoFe alloy and the forming of the second free layer of NiFe alloy further comprises forming the first free layer of CoFe alloy with a predetermined first thickness and forming the second free layer of NiFe with a predetermined second thickness, wherein the ratio of the predetermined first thickness to the predetermined second thickness is selected to provide a predetermined magnetostriction and wherein at least one of the CoFe alloy and NiFe alloy includes an addition of at least one element of B, P, Si, Nb, Zr, Hf, Ta and Ti, the ratio of the first thickness and second thickness being selected to provide a desired magnetostriction and the addition of at least one element of B, P, Si, Nb, Zr, Hf, Ta and Ti being controlled to maintain a substantially constant sensor resistance while adjusting the ratio of the first thickness and second thickness to provide a desired magnetostriction. - View Dependent Claims (2, 3, 4, 5)
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6. A magnetic sensor, comprising:
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a pinned layer; a separation layer formed over the pinned layer; a bilayer, composite free layer, the forming the bilayer, composite free layer includes; a first free layer, the first free layer comprising a CoFe alloy; and a second free layer, the second free layer comprising a NiFe alloy, wherein the first free layer of CoFe alloy and the second free layer of NiFe alloy further comprises the first free layer of CoFe alloy formed with a predetermined first thickness and the second free layer of NiFe formed with a predetermined second thickness, wherein the ratio of the predetermined first thickness to the predetermined second thickness is selected to provide a predetermined magnetostriction and wherein at least one of the CoFe alloy and NiFe alloy includes an addition of at least one element of B, P, Si, Nb, Zr, Hf, Ta and Ti, the ratio of the first thickness and second thickness being selected to provide a desired magnetostriction and the addition of at least one element of B, P, Si, Nb, Zr, Hf, Ta and Ti being controlled to maintain a substantially constant sensor resistance while adjusting the ratio of the first thickness and second thickness to provide a desired magnetostriction. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14)
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15. A magnetic storage system, comprising:
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a movable magnetic recording medium; a magnetic sensor for detecting magnetic signals on the moveable recording medium, comprising; a pinned layer; a separation layer formed over the pinned layer; a bilayer, composite free layer, the forming the bilayer, composite free layer includes; a first free layer, the first free layer comprising a CoFe alloy; and a second free layer, the second free layer comprising a NiFe alloy, a magnetoresistance detector, coupled to the magnetic sensor, for detecting an electrical resistance through the magnetic sensor based on magnetic orientations of the first and the second free layers; and an actuator, coupled to the magnetic sensor, for moving the sensor relative to the medium; wherein the first free layer of CoFe alloy and the second free layer of NiFe alloy further comprises the first free layer of CoFe alloy formed with a predetermined first thickness and the second free layer of NiFe formed with a predetermined second thickness, wherein the ratio of the predetermined first thickness to the predetermined second thickness is selected to provide a predetermined magnetostriction and wherein at least one of the CoFe alloy and NiFe alloy includes an addition of at least one element of B, P, Si, Nb, Zr, Hf, Ta and Ti, the ratio of the first thickness and second thickness being selected to provide a desired magnetostriction and the addition of at least one element of B, P, Si, Nb, Zr, Hf, Ta and Ti being controlled to maintain a substantially constant sensor resistance while adjusting the ratio of the first thickness and second thickness to provide a desired magnetostriction. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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Specification