Read Back Signals in Magnetic Recording - Research Group Fidler
Read Back Signals in Magnetic Recording - Research Group Fidler
Read Back Signals in Magnetic Recording - Research Group Fidler
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Analytical Calculations<br />
t<br />
C<br />
8<br />
π<br />
= . (3.15)<br />
Insert<strong>in</strong>g <strong>in</strong> (3.11) leads to the f<strong>in</strong>al result for the head field<br />
⎛γ x( x + gz , ) −γx( xz , ) −γx( − x+ gz , ) +γx( −xz<br />
, ) ⎞<br />
MSL t ⎜ ⎟<br />
H H ( xz , ) = ⋅ 0<br />
8 g ⎜ ⎟<br />
. (3.16)<br />
⎜γ z( x + gz , ) −γ z( xz , ) +γz( − x+ gz , ) −γz( −xz<br />
, ) ⎟<br />
⎝ ⎠<br />
Now a normalized head field H H can be <strong>in</strong>troduced, which is <strong>in</strong>dependent from the sensor<br />
magnetization<br />
H<br />
n<br />
H<br />
⎛γ x( x + gz , ) −γ x( xz , ) −γ x( − x+ gz , ) + γ x(<br />
−xz<br />
, ) ⎞<br />
t ⎜ ⎟<br />
( xz , ) = ⋅ 0<br />
8 g ⎜ ⎟<br />
. (3.17)<br />
⎜<br />
z( x + gz , ) − z( xz , ) + z( − x+ gz , ) − z(<br />
−xz<br />
, ) ⎟<br />
⎝γ γ γ γ ⎠<br />
Figure 3.3 shows the normalized head field at z = − 10 nm and for t = 5 nm and g = 27.5 nm ,<br />
so that the total gap is 60 nm. For longitud<strong>in</strong>al record<strong>in</strong>g only the x-component contributes,<br />
because the magnetization po<strong>in</strong>ts ma<strong>in</strong>ly <strong>in</strong> this direction.<br />
H x<br />
0.06<br />
0.04<br />
0.02<br />
0.00<br />
-0.02<br />
-0.04<br />
-0.06<br />
-100 -50 0 50 100<br />
x [nm]<br />
H z<br />
-0.02<br />
-100 -50 0 50 100<br />
x [nm]<br />
Figure 3.3: The x- and the z-component of the normalized head field of a read head with<br />
60 nm gap, and sens<strong>in</strong>g layer thickness 5 nm, 10 nm below the ABS.<br />
0.06<br />
0.05<br />
0.04<br />
0.03<br />
0.02<br />
0.01<br />
0.00<br />
-0.01<br />
33