Relations between coercivity and recording performances for Ba-ferrite particulate perpendicular media

Abstract

Recording performances for Ba-ferrite particulate perpendicular magnetic tapes, with different coercivity values, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H_{c\perp}</tex> =470- 1930 Oe, and other properties substantially unchanged, were investigated with ring-shaped heads. Noise was found to be independent of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H_{c\perp}</tex> . It was ascertained that reproduced voltages and signal-to-noise ratios were constant and highest for <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H_{c\perp} &gt; H_{co\perp}, H_{co\perp}</tex> being 600 - 700 Oe depending on recorded wavelength, and that they decreased in proportion to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H_{c\perp}</tex> for <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H_{c\perp} &lt; H_{co\perp}</tex> . Therefore, Ba-ferrite tapes can be designed, with their highest performances, to adjust their coercivity so as to meet ferrite or metal head recording ability.