The above mentioned and other features of this invention and the manner of obtaining them will become more apparent, and the invention itself will be best understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, in which:
a), 4(b) and 4(c) are explanatory diagrams showing a manufacturing method of a magnetoresistive element of the present invention when the sub-ferromagnetic layers are magnetized in the direction of 180° within the film surface to the direction of the longitudinal bias field.
a), 5(b) and 5(c) are explanatory diagrams showing a method of manufacturing a magnetoresistive element when some sub-ferromagnetic layers are magnetized in the direction of 90° within the film surface to the direction of the longitudinal bias field.
a) is a diagram of a disk drive having the magnetoresistive element of the present invention.
b) is a diagram of a head slider used in the disk drive of
As seen in
The sub-ferromagnetic layers 15a, 15b, and 15c may also be formed of CoPt, and the magnetic separation layers 18a, 18b may be formed of Cr, W. The free layer is formed of CoFe, the intermediate layer may be formed of an insulating material such as Al2O3, and the antiferromagnetic layer may be formed of IrMn. In addition, the pinned layer 12 may be formed in the double-layer structure of CoFe/Ru/CoFe including an intermediate material such as Ru. Furthermore, an underlayer of Ta or the like may be provided to the antiferromagnetic layer 13, with a cap layer of Ta or the like applied to the free layer 11. In addition, these magnetoresistive elements may also be laminated in the inverse sequence.
The sub-ferromagnetic layers 15a, 15b, and 15c are formed having different coercive forces. In this embodiment, the coercive forces of the sub-ferromagnetic layers 15a, 15b, and 15c respectively have 1500 Oe (H1), 2500 Oe (H2), and 2000 Oe (H3) through formation thereof using different film forming conditions. The coercive force of each magnetic layer may be varied within the range of about 1000 to 3000 Oe depending on differences in the composition of material, film forming condition, and underlayer (magnetic separation layer). Since the magnetic layers of different coercive forces are laminated, the intensity of the longitudinal bias field applied to the free layer can be adjusted with the method explained later, after formation of the composite ferromagnetic layer.
As shown in
A method for adjusting the longitudinal bias field to the free layer from the composite ferromagnetic layer is shown in
As shown in
The effective magnetic field applied to the ferromagnetic layer can be reduced when the external magnetic fields Ha, Hb, and Hc are partially absorbed by a magnetic shield. However, in this case, when the effective magnetic fields are assumed respectively as Ha′, Hb′, and Hc′, a higher external magnetic field must be applied to provide the results of Ha′>H2, H1<Hb′<H3, H3<Hc′<H2. This is also true in the case where the external magnetic field is applied in the direction of 90° to the direction of the longitudinal bias field.
Magnetization of the sub-ferromagnetic layer 15a or sub-ferromagnetic layers 15a, 15c is oriented in the same direction as the external magnetic field 17d or 17e by applying the external magnetic field 17d in the intensity of Hb=1700 Oe (H1<Hb<H3) or the external magnetic field 17e in the intensity of Hc=2200 Oe (H3<Hc<H2) in the direction of 90° within the film surface to the direction of the longitudinal bias field, as shown in
With a combination of 180° and 90° rotation shown in
Since the longitudinal bias field can be lowered with the external magnetic field as explained above, the optimum longitudinal bias field can be attained easily, for example, by reducing generation of Barkhausen noise by first increasing the longitudinal bias field by about ten percent more than the ordinary field and then introducing the manufacturing method of the present invention individually to a magnetic head if it cannot provide sufficient output. Moreover, the longitudinal bias field which is once reduced can also be recovered to the initial intensity thereof by remagnetization.
The magnetoresistive element and manufacturing method thereof of the present invention can be applied in common to the magnetoresistive element provided with a layer (free layer) which changes freely in the direction of magnetization in response to the field of media such as a spin valve type element and a tunnel magnetoresistive element and to the manufacturing method thereof.
Moreover, the magnetoresistive element and manufacturing method thereof may be used not only for the magnetic head for reading the magnetic field of a medium but also for magnetic devices such as MRAM. In addition, the magnetoresistive element and manufacturing method thereof of the present invention can be used not only for horizontal magnetic recording type magnetic head shown in
The magnetoresistive element of the present invention can be used in a hard disk drive, an example of which is shown in
A head slider 28 is located at the distal end of the suspension 26, and includes a read/write element 30. The read head in the read/write element 30 is the magnetoresistive element of the present invention. Information recorded on the disk 22 is read by the magnetoresistive element as the disk rotates and the actuator moves the magnetoresistive element across predetermined tracks on the disk. A control system 32 includes controllers, memory, etc. sufficient to control disk rotation, actuator movement and read/write operations, in response to commands from a host (not shown).
While the principles of the invention have been described above in connection with specific apparatus and applications, it is to be understood that this description is made only by way of example and not as a limitation on the scope of the invention.
Number | Date | Country | Kind |
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2006-223981 | Aug 2006 | JP | national |