Pole tip

Heads are randomly sampled for pole tip geometry measurements after lapping and good individual sliders are sorted out. 

If we examine the magnetic held from such a quadrupolar device, we will hnd that the held along the central axis is exactly zero and increases linearly to a maximum value at each pole face. (The pole tips should be hyperbolic surfaces to conform to the shape of the magnetic held, although cylindrical pole tips are often used for ease of manufacture.) Quadrupole magnets are thus characterized by the gradient of the magnetic held, dB/dr, where r is a radial coordinate and... 

The deposition and patterning of the bottom magnetic pole follows. It is usually electroplated with a through photoresist-window frame mask to a thickness level of 2-4pm. Note that tire magnetic pole is made into a pancake shape in order to increase the head efficiency, while the narrow pole tip s dimension is the one that determines the narrow track width. As stated, the widely used Co-based alloy magnetic poles are electrodeposited (wet process) and the nanocrystalline FeN based alloys are sputter deposited in a vacuum chamber (dry process). 

As in step 2, this step consists of the deposition and patterning of the top magnetic pole (2-4-pm thick) and the overpass lead, which provides electrical cormection to the central tap of the coils. The back regions of the magnetic poles are, as a rule, made thicker than the pole tips to aclueve high head efficiency and avoid magnetic saturation. 

Fig. 8.1 (a) Schematic illustration ol thin film head with a helical coil at the main pole tip. (b) Dependence of field distribution on coil recession height, h [2]. 1999 IEEE... 

As the head track width decreases, remanent magnetization of the main pole tip is likely to occur because of stress-induced anisotropy and increased shape anisotropy in the normal direction to the ABS. The field from this remanent magnetization can... 

Fig. 8.15 (a) Variation of pole tip structure Type / - tapered structure in both down and cross track directions Type //-tapered only in the down track direction Type III-no tapered structure, (b) Comparison of head fields for tapered main poles of various types... 

FeCo - in particular with a 2 % V addition - has found widespread use as a magnetically soft material with a high saturation induction, e.g. as electromagnet pole tips, and the respective alloys are known as Permendur alloys (Chen, 1961 Kouvel, 1967 Dietrich, 1990). These alloys also exhibit a high, positive magnetostrictive co-... 

By adding sectors to the pole tips as shown in O Fig. 50.18, an azimuthal variation is induced in the magnetic field. Since the magnetic field varies with the azimuthal angle, so must... 

Fig. 12. The Co37pe53 pole tip nanostructures with 50 nm critical dimensions produced with two different pulse currents (A) puise = 18mAcm , E —1.24 V, (B) jp = 25mAcm , E —1.35V. Potentials are quoted vs SCE, the saccharin coverage in A is 95% and in B 30% during the pulse current stage. Duty cycle 20%. Reprinted from Ref. 4 with permission. Copyright (2006) IEEE.

The first major component of the experimental apparatus, the 48D48 magnet, is in place and has ben powered up. The field shaping pole tips and field clamp assembly, designed at CMU and purchased by the AGS, performed as anticipated (See Sect IX.G). Layout of shielding walls, cable trays, and electronics areas will begin in August. 

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