Effects of SiO2 Addition in FePt on Microstructures and Magnetic Properties on Two Different MgO Substrates

Abstract

Ordered FePt film is attractive for its very high perpendicular anisotropy. In the present study, we report different texture formation and mechanisms of ordering FePt films on MgO (100) single crystal (A) substrates and MgO (200) polycrystalline film formed on SiO2/Si (B) substrates with and without SiO2 addition. Films with structure of [0.24 nm Pt/0.25 nm Fe/0.21 nm SiO2](15) were deposited on 600 degrees C substrates and subsequently treated by rapid thermal annealing. In the as-deposited state, FePt grain size was smaller and its degree of ordering was lower on substrate (B) than substrate (A) regardless of SiO2 addition. Upon annealing, grain growth was more significant on substrate (A) than on substrate (B), and degree of ordering kept nearly constant. However, in the case of SiO2 addition, upon annealing, grain growth was more significant on substrate (B) than substrate (A), and the ordering parameter increased on both substrates (A) and (B). This indicates ordering reaction is dominated by phase separation of Mg,O or MgO incorporated in FePt grains of the as-deposited states during the short time rapid annealing treatments. Different texture formation and grain size difference in the two different substrates will be discussed together with the mechanism of ordering in FePt films.