CoNiPd Magnetic Intermediate Layers for CoPt-TiO2 Perpendicular Recording Media

Abstract

The present CoCrPt-oxide type granular media require Ru intermediate layer (IL) to ensure c-axis alignments of CoCrPt grains and for good magnetic isolation among grains. Double layered Ru IL composed of Ru1 deposited at lower Ar pressure and Ru2 deposited at higher Ar pressure (10 mTorr order) is used more recently. However, thickness of the Ru is presently in the range of 16 nm to 20 nm and reduction of the thickness is important in the view of writability as well as production cost. In the present work, we have introduced (111) textured semi-soft magnetic CoNiPd film of fcc structure to substitute bottom side of Ru IL (Ru1). Instead of the doubled Ru1(10 nm)/Ru2(10 nm) IL structure, CoNiPd(t nm)/Ru2(10 nm) IL structure was studied by varying CoNiPd thickness. When Co16Ni19Pd65 (10 nm)/Ru2 was used as the intermediate layer instead of the conventional Ru1(10 nm)/Ru2(10 nm), CoPt-TiO2 layer showed similar coercivity and average grain size but slightly deteriorated c-axis alignment and wider grain size distribution. With further increase of the CoNiPd thickness, coercivity of the CoPt-TiO2 increased but average grain size and grain size distribution increased.