Magnetic properties of vacuum deposited Co-Cr perpendicular media and their recording performances

To clarify the magnetic properties required for the continuously vacuum deposited Co-Cr single layer media, the dependence of reproduced voltage using the ferrite ring heads on Hkeff,
Hc\perp
, Ms and thickness is studied. The media with Hkeff of 2 - 4.5 kOe,
Hc\perp
of 500 - 700 Oe, Ms of 300 - 600 emu/cc and thickness more than 0.2 μm yield high reproduced voltage and high CN ratio at high linear density over 100 kFRPI. Even the media with
Hc\perp
less than 200 Oe have high reproduced voltage, but media noise is high too. Besides the above factors, it is found that the shearing of the perpendicular hysteresis loops measured by VSM affects the recording performances. The shearing slope of the loops is about
1/3\pi
for the perpendicular anisotropy media which have high reproduced voltage at high linear density. The CN ratio of 45 dB is obtained at 130 kFRPI by use of a narrow track ferrite head with track width of 5 μm at the medium-head relative speed of 3 m/s.