High coercivity in Co-Cr films for perpendicular recording prepared by low temperature sputter-deposition

Hc_⊥ over 1000 Oe has been achieved for Co-Cr films deposited at room temperature and at an extremely high Ar pressure onto a Ti underlayer. Conditions for further high Hc_⊥ were studied. After optimization of the Ti underlayer thickness, an Hc⊥ of 1370 Oe was obtained for Co-Cr films of 45 nm thick, in which a high c-axis orientation could be sustained by hetero-epitaxial growth. Magnetic isolation of columns was realized by a voided structure by shadowing effect at high deposition pressures and oxide formation. The high Hc_⊥ is determined by large perpendicular anisotropy, grain size and the magnetic isolation of columns, but the isolation manner very differs from the micro-segregation of Cr in conventional high Hc films deposited at high temperatures and low pressures,