Stacked Structure Media for High Density Perpendicular Recording

Abstract

Perpendicular magnetic recording media with a new stacked media structure are proposed in this study. A distinct magnetically isolated granular Co-Pt-TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> film and a Co-Pt top layer for controlling an exchange coupling of the granular film were used to realize the stacked layer. By adding the top Co-Pt layer, H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> (saturation field) becomes small with reduced DeltaH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> /H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> (narrower magnetic anisotropy distribution) and increased K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">u</sub> V/k <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</sub> T (enhanced thermal stability). By changing Ar gas pressure of the top layer deposition, the exchange coupling of the granular layer could be precisely controlled. Film microstructure analysis revealed that a Co-Pt top layer deposited at high Ar gas pressure forms a granular structure. On the other hand, low gas pressure deposition formed a continuous structure with grains connected each other similar to a continuous layer of the CGC (coupled granular continuous) media