Self-Stabilized Carbon-$L{{1}}_{0}$ FePt Nanoparticles for Heated Dot Recording Media

Heated dot magnetic recording (HDMR) technology promises to achieve ultrahigh storage density well above 4 Tb/in
²
by making use of L1
₀
FePt bimetallic islands. HDMR media require the development of thermally stable, noninteracting magnetic patterns to circumvent the signal noise and writability challenges. We prepared self-stabilized carbon-L10 FePt nanoparticles (NPs) with average diameter of about 7.2 nm for the HDMR media. FePt NPs synthesized by chemical reduction using oleic acid and oleylamine transform to the carbon-L1
₀
FePt phase with optimized heat treatment at 873 K. The high-temperature annealing not only helps to achieve the desired L1
₀
phase but also helps in the formation of a carbon coating on the FePt NPs due to degradation of the organic cap. We investigated the effect of carbon coating on the electronic states of Fe using X-ray absorption measurements and corroborated with high-resolution transmission electron microscopy and Fourier-transform infrared spectroscopy. X-ray magnetic circular dichroism reveals the presence of magnetocrystalline anisotropy in the carbon-L1
₀
FePt NPs, which is also supported by the structural and magnetic measurements. A magnetization-field loop at 300 K shows high coercivity of ≅ 1.6 T. The synthesized carbon-L1
₀
FePt NPs can be used as FePt islands and should be suitable for high-density HDMR media.