Fabrication of $\hbox{L}1_{2}\hbox{–}\hbox{CrPt}_{3}$ Alloy Films Using Rapid Thermal Annealing for Planar Bit Patterned Media

SiO
₂
(2 nm)/Cr
₂₅
Pt
₇₅
(15 nm) and SiO
₂
(2 nm)/Cr
₂₅
Pt
₇₅
(15 nm)/SiO
₂
(10, 20 nm)/Co
₈₀
Zr
₁₀
Nb
₁₀
(10 nm) were prepared by magnetron sputtering method and post-annealed by rapid thermal annealing (RTA) at temperatures of 600°C-1000°C for 1-60 sec. The saturation magnetization M
_s
and coercivity H
_c
measured by applying a maximum field of 18 kOe were 150 emu/cc and 12 kOe, respectively, for the sample after rapid thermal annealing at 1000 °C for 30 sec. This means that L1
₂
-CrPt
₃
phase was obtained by RTA process. The RTA process was applied to fabricate the multilayered structure having L1
₂
-CrPt
₃
and CoZrNb soft magnetic underlayer (SUL). The polar Kerr loop of CrPt
₃
(15 nm)/SiO
₂
(20 nm)/CoZrNb(10 nm) after RTA at 1000°C for 30 sec exhibited a large coercivity H
_c
> 9 kOe corresponding to that of the CrPt
₃
single layer. From the compositional depth profile of CrPt
₃
(15 nm)/SiO
₂
(20 nm)/CoZrNb(10 nm) processed by RTA at 1000°C for 30 sec, sharp layered structure was confirmed despite the high-temperature heat treatment. When the SiO
₂
thickness was reduced to 10 nm, such a layered structure was completely destroyed due to the interdiffusion between CrPt
₃
and CoZrNb layers. Thus it was concluded that the RTA process and the interlayer of SiO
₂
(20 nm) were effective to fabricate layered structure having L1
₂
-CrPt
₃
and SUL.