Exchange-Coupled Composite Media

The proposal of exchange-coupled composite (ECC) media dates back to 2005, when two different papers independently proposed to exploit the old concept of "exchange-spring magnet" to improve the writability of perpendicular recording media. These papers suggested adding a soft magnetic layer to the hard magnetic media, thus exploiting the hard-to-soft exchange-coupling to reduce the media writing field and keep high thermal stability. This chapter recalls the magnetic behavior and main advantages of composite hard/soft systems (section 5.2) and reviews the most important results so far obtained on ECC conventional media (section 5.3), ECC media based on FePt (section 5.4) and graded anisotropy media (section 5.5).