Read Back Signals in Magnetic Recording - Research Group Fidler

FEM Simulations
approximately to the exchange coupling with the pinned layer for a 8 nm IrMn
antiferromagnet. The two shields are assumed to be made of Permalloy (NiFe) with
Shields
spontaneous polarization J = 1T,
and their dimensions are 50 nm× 100 nm× 50 nm . The
s
gap between the two shields is 60 nm. The Gilbert damping constant for the whole model is
always 0.1 unless otherwise noted. The exchange constants are
PL
A
−11
= 1.2⋅ 10 J/m ,
HB
A
are summarized in Table 6.1.
−11
= 1.0⋅ 10 J/m , and
Shields
A
FL
A
−11
= 1.3⋅ 10 J/m ,
−11
= 1.3⋅ 10 J/m . All magnetic properties
The GMR element of the model is meshed with a size of 5 nm. The mesh of the shields has a
general size of 50 nm, but it is refined near the gap and near the track region.
Figure 6.1: The magnetic model used for the FEM calculations. The mesh size for the
shields (green) is 50 nm, and is refined to 5 nm near the track and near the spin valve
layers. The hard bias magnets (purple), the free layer (dark blue), and the pinned layer
(light blue) are also meshed with triangle size of 5 nm.
z
y
x
66