Co-γFe2O3/NiO Perpendicular Magnetic Recording Media

Abstract

A study on Co-γFe2O3/NiO perpendicular magnetic anisotropic media was reviewed focusing on their fabrication process, crystallographic and magnetic properties, and recording characteristics. The media were prepared using reactive sputtering in Ar+O2 mixture gas and annealing in air at lower process temperature than 350°C. The NiO underlayer deposited in room temperature had NaCl-like structure with <100> orientation. The Co-γFe2O3 layer prepared onto the NiO underlayer had also <100> orientation. The media have large perpendicular anisotropy energy of 1-3×106 erg/cm3 which was originated from preferential crystalline orientation of <100> axis of Co-γFe2O3and tensile stress at the Co-γFe2O3/NiO interface. The perpendicular coercivity of the media was widely changeable from 0.8 kOe to 6 kOe. The media was mechanically strong enough to use in sliding contact recording mode without protective overcoat layer. The media had excellent ultra-high-density recording performance, showing D50 over 150kFRPI and low media noise. It is concluded that the Co-γFe2O3/NiO medium is one of the promising candidates to achieve ultra-high-density recording.