<s>
Exchange	B-General_Concept
spring	I-General_Concept
media	I-General_Concept
(	O
also	O
exchange	B-General_Concept
coupled	I-General_Concept
composite	I-General_Concept
media	I-General_Concept
or	O
ECC	O
)	O
is	O
a	O
magnetic	B-Architecture
storage	I-Architecture
technology	O
for	O
hard	B-Device
disk	I-Device
drives	I-Device
that	O
allows	O
to	O
increase	O
the	O
storage	O
density	O
in	O
magnetic	B-Architecture
recording	I-Architecture
.	O
</s>
<s>
The	O
idea	O
,	O
proposed	O
in	O
2004	O
by	O
Suess	O
et	O
al.	O
,	O
is	O
that	O
the	O
recording	O
media	O
consists	O
of	O
exchange	B-General_Concept
coupled	O
soft	O
and	O
hard	O
magnetic	O
layers	O
.	O
</s>
<s>
Exchange	B-General_Concept
spring	I-General_Concept
media	I-General_Concept
allows	O
a	O
good	O
writeability	O
due	O
to	O
the	O
write-assist	O
nature	O
of	O
the	O
soft	O
layer	O
.	O
</s>
<s>
Hence	O
,	O
hard	O
magnetic	O
layers	O
such	O
as	O
FePt	O
,	O
CoCrPt-alloys	O
or	O
hard	O
magnetic	O
multilayer	O
structures	O
can	O
be	O
written	O
with	O
conventional	O
write	B-Device
heads	I-Device
.	O
</s>
<s>
The	O
required	O
thickness	O
of	O
the	O
hard	O
layer	O
for	O
best	O
thermal	O
stability	O
is	O
the	O
exchange	B-General_Concept
length	O
of	O
the	O
hard	O
layer	O
material	O
.	O
</s>
<s>
The	O
first	O
experimental	O
realization	O
of	O
exchange	B-General_Concept
spring	I-General_Concept
media	I-General_Concept
was	O
done	O
on	O
Co-PdSiO	O
multilayers	O
as	O
the	O
hard	O
layer	O
which	O
was	O
coupled	O
via	O
a	O
PdSi	O
interlayer	O
to	O
a	O
FeSiO	O
soft	O
layer	O
.	O
</s>
<s>
Besides	O
the	O
improved	O
writeability	O
,	O
another	O
advantage	O
of	O
exchange	B-General_Concept
spring	I-General_Concept
media	I-General_Concept
is	O
,	O
that	O
the	O
switching	O
field	O
distribution	O
of	O
the	O
grains	O
,	O
which	O
has	O
to	O
be	O
as	O
small	O
as	O
possible	O
to	O
allow	O
for	O
high	O
storage	O
densities	O
,	O
can	O
be	O
decreased	O
.	O
</s>
<s>
This	O
effect	O
was	O
predicted	O
theoretically	O
and	O
experimentally	O
verified	O
on	O
Co/Pd	O
multilayers	O
as	O
hard	O
layer	O
coupled	O
to	O
Co/Ni	O
multilayers	O
as	O
soft	O
layer	O
.	O
</s>
<s>
In	O
commercial	O
hard	B-Device
disks	I-Device
exchange	B-General_Concept
spring	I-General_Concept
media	I-General_Concept
is	O
used	O
since	O
about	O
2007	O
.	O
</s>
