Patent Application
20080037183
For a fuller understanding of the nature and advantages of this invention, as well as the preferred mode of use, reference should be made to the following detailed description read in conjunction with the accompanying drawings which are not to scale.
The following description is of the best embodiments presently contemplated for carrying out this invention. This description is made for the purpose of illustrating the general principles of this invention and is not meant to limit the inventive concepts claimed herein.
Referring now to
At least one slider 113 is positioned near the magnetic disk 112, each slider 113 supporting one or more magnetic head assemblies 121. As the magnetic disk rotates, slider 113 moves radially in and out over the disk surface 122 so that the magnetic head assembly 121 may access different tracks of the magnetic disk where desired data are written. Each slider 113 is attached to an actuator arm 119 by way of a suspension 115. The suspension 115 provides a slight spring force which biases slider 113 against the disk surface 122. Each actuator arm 119 is attached to an actuator means 127. The actuator means 127 as shown in
During operation of the disk storage system, the rotation of the magnetic disk 112 generates an air bearing between the slider 113 and the disk surface 122 which exerts an upward force or lift on the slider. The air bearing thus counter-balances the slight spring force of suspension 115 and supports slider 113 off and slightly above the disk surface by a small, substantially constant spacing during normal operation.
The various components of the disk storage system are controlled in operation by control signals generated by control unit 129, such as access control signals and internal clock signals. Typically, the control unit 129 comprises logic control circuits, storage means and a microprocessor. The control unit 129 generates control signals to control various system operations such as drive motor control signals on line 123 and head position and seek control signals on line 128. The control signals on line 128 provide the desired current profiles to optimally move and position slider 113 to the desired data track on disk 112. Write and read signals are communicated to and from write and read heads 121 by way of recording channel 125.
With reference to
With reference now to
The sensor 300 includes a sensor stack 302 which is sandwiched between first and second leads 304, 306. The leads 304, 306 are constructed of an electrically conductive material and may be constructed of a material that is magnetic as well (such as NiFe) so that the leads 304, 306 can function as magnetic shields as well as leads.
First and second side insulation layers 308, 310 are provided at either lateral side of the sensor 302, filling most of the space between the leads 304, 306. The side insulation layers 304, 306 may be constructed of, for example, alumina (Al2O3). First and second overlay insulation layers 312, 314 are also provided. The overlay insulation layers 312, 314 extend over outer portions of the sensor stack 302, and may extend over the side insulation layers 308, 310 as well. The overlay insulation layers 312, 314 terminate at inner ends, which are separated by a width W2. As can be seen, the second lead 306 contacts the top of the sensor stack 302 in a location between the first and second overlay insulation layers 312, 314, having a contact width W2. The sensor stack 302 has a physical width W1 that is significantly larger than the width W2 between the inner ends of the overlay insulation layers 312, 314.
Because the current flowing from the second lead 306 is limited to an area having a width W2 between the overlay insulation layers 312, 314, the effective sensor track width is smaller than the actual width W1 of the sensor. However, due to the spreading of current as it passes through the sensor stack 302, the effective track width will be larger than the width W2 between the overlay insulation layers 312, 314. Therefore, the effective track width of the sensor 300 will be somewhere between W2 and W1.
As can be seen, the effective track width will be removed inward from the outer edges 316, 314 of the sensor stack 302. As mentioned above, the outer edges 316, 318 of the layers of the sensor stack can become damaged during manufacture so that the magnetic qualities of the sensor layers at the outer edges is much poorer than at the inner portions of the sensor stack 302. Because the effective track width of the sensor 300 is removed inward from the outer edges 316, 318 of the sensor stack 302, the sensor 300 can enjoy a narrow track width while also being unaffected by any damage to the outer edges of the sensor stack 302.
With continued reference to
The pinned layer structure 322, can be of various configurations, and is preferably an antiparallel coupled (AP coupled), AFM pinned structure, that includes first and second magnetic layers AP1326, AP2328 which are antiparallel coupled across an AP coupling layer 330 such as Ru. The AP1 and AP2 layers 326, 328 can be, for example CoFe or some other magnetic material. The AP1 layer 326 is exchange coupled with a layer of antiferromagnetic material (first AFM layer) 332 such as PtMn, IrMn, etc. The exchange coupling with the AFM layer strongly pins the magnetization 334 of the AP1 layer 326 in a desired direction perpendicular to the ABS. Antiparallel coupling between the AP1 layer and the AP2 layer pins the magnetization 336 of the AP2 layer 328 in a direction perpendicular to the ABS and antiparallel with the magnetization 334 of the AP1 layer 326. A seed layer 338 may be provided at the bottom of the sensor stack to initiate a desired crystalline growth in the layers deposited there over.
With reference still to
Because the sensor 300 is a CPP structure, sense current will not be shunted through the second AFM layer 340 as would be the case in a CIP structure. With reference to
While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. Other embodiments falling within the scope of the invention may also become apparent to those skilled in the art. Thus, the breadth and scope of the invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.
