US6,266,218(Magnetic sensors having antiferromagnetically exchange-coupled layers)

US6266218(IBM)

作られている、構成される、成る、有する：
1) The longitudinal bias structure is built up of a top ferromagnetic bias layer ..., a bottom ferromagnetic bias layer ..., and an exchange-coupling layer disposed between the top and bottom bias layers.

2) The longitudinal bias structure of claim 8, wherein said exchange-coupling layer is made of a material selected from the group consisting of Ru, Cr, Rh, Cu.

3) wherein at least one of said top ferromagnetic bias layer and said bottom ferromagnetic bias layer comprises a material selected from the group consisting of Co, Fe, Ni and alloys of Co, Fe and Ni. （から構成される）

4) wherein said bottom ferromagnetic bias layer comprises a portion of said free layer（を構成する）

5) Exchange-coupling layer 16 is made of a non-magnetic material, e.g., a transition metal or an alloy containing a transition metal capable of inducing anti-parallel coupling between top layer 12 and bottom layer 14.

作製する：
known techniques for fabricating magnetoresistive readback sensors（fabricateは捏造の意味があるからmanufactureによく直されたが、実例は多い）

（図面）ページに向かう（から出る）方向：
FIG. 1A shows a typical GMR readback sensor according to the prior art. The sensor has a high coercivity ferromagnetic pinned layer 4 with a fixed magnetic moment pointing unto the page and a low coercivity ferromagnetic free layer 5 with a movable magnetic moment, which can rotate from pointing into the page to pointing out of the page.

生じる：
When free layer 5 is allowed to have more than one magnetic domain, then it experiences Barkhausen jumps and other domain reorientation phenomena during magnetic reversal as when responding to external magnetic fields encoding data in a magnetic recording disk. This problem is also known in the art and is highly undesirable as it produces noise and worsens the signal-to-noise ratio (SNR) of the sensor.

方策、方式、手段：
In order to provide the longitudinal biasing field and prevent Barkhausen noise several schemes have been employed.

参照：
For more details on this longitudinal biasing scheme the reader is referred to U.S. Pat. No. 5,528,440 to Fontana et al.

must, should, require:
In order to increase the data density, the thickness of the free layer must be decreased. For a data density of about 3 Gb/in.sup.2, the free layer should have a magnetic moment equivalent to that of about 70 Angstroms of Ni.sub.80 Fe.sub.20 alloy; for a data density of about 40 Gb/in.sup.2, the free layer should have a thickness equivalent to about 45 Angstroms of Ni.sub.80 Fe.sub.20 alloy.Reducing the thickness (and therefore M.sub.r T.sub.free) of the free layer requires a corresponding reduction in the M.sub.r T.sub.bias of the hard bias layers. Specifically, the proportionality constant between the free layer M.sub.r T.sub.free and hard bias M.sub.r T.sub.bias (i.e. 1.7) should be roughly preserved, although the exact value depends on specific geometric considerations. （英訳時に同様に使えるかどうか・・・？）

問題：
problems are encountered when one attempts to ...

代名詞：
The M.sub.r T.sub.bias value of the hard bias layer can be reduced by decreasing its thickness. However, this is undesirable because it reduces the coercivity of the hard bias layer, making it susceptible to external fields and its own demagnetizing fields and thus making it less effective at suppressing Barkhausen noise.

必要性：
Finally, there exists a need in the art of micromagnetic sensors for a longitudinal biasing structure that is capable of providing longitudinal biasing of extremely thin ferromagnetic films. Such a longitudinal biasing structure would facilitate the use of magnetic readback sensors in data storage devices having extremely high data densities.

作用：
when there is no applied magnetic field acting on structure 10

自動詞：
Because the magnetizations of bias layers 12, 14 are anti-parallel they subtract and thus reduce an overall or net magnetic moment of structure 10. （双方の磁化は減算され）