Abstract
We demonstrated formation of magnetic nanodots (NDs) made of FePt alloy by exposing a metal bi-layer stack to remote H2 plasma and characterized their magnetization properties. Pt/Fe bi-layer stacked structures formed on SiO2 were exposed to remote H2 plasma generated by inductive coupling with an external single-turn antenna connected to a 60-MHz generator. After the remote H2 plasma exposure, the formation of electrically isolated FePt-NDs with an areal density of ～1011 cm-2 was confirmed. These results imply that surface migration and agglomeration of Fe and Pt atoms induced by remote H2 plasma is promoted simultaneously with the alloying reaction. The FePt-alloy NDs exhibited a large perpendicular anisotropy with an out-of-plane coercivity of ～4.8 kOe, while the in-plane and out-of-plane coercivities of the Pt/Fe bi-layer were almost zero, reflecting the small magneto-crystalline anisotropy of the Fe layer.
