Percolated perpendicular medium of FePt‐MgO/MgO bilayer films for ultra‐high magnetic recording

Abstract

Percolated perpendicular (FePt) 100-x -(MgO) x thin films with x = 0-10.07 vol.% were fabricated on glass substrate with MgO(200)underlayer. When the substrate temperature was 580 o C, a significant enhancement in coercivity was observed at 1.23 vol.% of MgO, which was due to the precipitation of MgO in FePt film causing the hindrance in domain wall motion. As the amount of MgO was increased above 1.23 vol.%, the percolated perpendicular structure began to transform into granular perpendicular structure. Meanwhile, the MgO was found to segregate along grain boundaries of FePt grains, leading to the reduction of FePt grain size. As a result the coercivity and ordering parameter became smaller. In this study the percolated perpendicular medium using FePt film with doping adequate amount of MgO has shown possibility to be an efficient method to increase recording density if the film processing conditions are optimized further.

Comparative evaluation of performance of percolated perpendicular media using FePt–MgO/Pt/Cr trilayer and FePt–MgO/MgO bilayer

“…The L1 0 (0 0 2) peak transformed gradually to the (2 0 0) peak as x was increased, revealing that the magnetic easy-axis tilted from perpendicular to the in-plane direction. In the MgO underlayered series, the crystal orientation shows insensitive to the MgO dopant content [15]. However, the alignment of crystal orientation in the MgO series is weaker than in the Pt series, as evidenced by the wider FWHM.…”

“…Since FePt magnetic layer on different underlayers, Pt(0 0 1) and MgO(0 0 2) exhibits extensive ordering at different substrate temperatures [12,15], the deposition temperatures of the Pt and MgO underlayered samples were set to 420 and 580 1C, respectively. Composite (FePt) 100Àx -(MgO) x films (x ¼ 0-6.13 vol%) were magnetron-sputtered with a background vacuum of under 6.7 Â 10 À7 Pa. Before the FePt-MgO film was deposited, Pt(0 0 1)/ Cr(0 0 2) and MgO(0 0 2) underlayers were deposited at 350 1C and room temperature, respectively.…”