Anti-parallel coupled soft under layers for high-density perpendicular recording

A promising soft magnetic under layer (SUL) structure consisting of anti-parallel coupled soft layers (APS) is investigated to improve the performance of high-density perpendicular recording media. CoCrPt-O recording media with average grain diameter ∼6 nm, coercivity of 5 kOe and nucleation field of -2 kOe is fabricated on both conventional SUL and APS. Wide-area adjacent track erasure (ATE) is observed for conventional SUL, which increases at lower interlayer spacing (t_IL). APS structure enables the suppression of ATE even up to t_IL=10 nm. Moreover, APS leads to reduced dc erase noise and improved signal to noise ratio particularly for SUL thicknesses <100 nm.