title: Probing the role of carbon microstructure on the thermal stability and performance of ultrathin (<2 nm) overcoats on L10 FePt media for heat-assisted magnetic recording.
abstract: An understanding of the factors influencing the thermal stability of ultrathin carbon overcoats (COCs) is crucial for their application in heat-assisted magnetic recording (HAMR) at densities ≥ 1 Tb/in(2). Two types of non-hydrogenated ultrathin (∼1.5 nm) COCs were investigated after being subjected to laser-induced localized heating (at temperatures > 700 K) as envisaged in HAMR. Filtered cathodic vacuum arc (FCVA)-processed carbon with tuned C(+) ion energies of 350 eV followed by 90 eV provides significantly higher sp(3) C-C hybridization than magnetron sputter deposition even at very low thicknesses of ∼1.5 nm. As a result, the FCVA-deposited ultrathin carbon overcoats displayed excellent thermal stability along with improved wear and corrosion resistance. On the other hand, the sputtered carbon exhibited carbon loss and topographical and structural changes after laser irradiation owing to lower sp(3) hybridization. Therefore, this study highlights the pivotal role of carbon microstructure, primarily sp(3) hybridization, in non-hydrogenated carbon overcoats to maintain excellent thermal stability during the recurring high-temperature cycles in a HAMR process.
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore , 21 Lower Kent Ridge Road, Singapore 117583, Republic of Singapore.
authors.forename: Shreya
authors.initials: S
authors.lastname: Kundu
authors.forename: Neeraj
authors.initials: N
authors.lastname: Dwivedi
authors.forename: Nalam
authors.initials: N
authors.lastname: Satyanarayana
authors.forename: Reuben J
authors.initials: RJ
authors.lastname: Yeo
authors.forename: Joachim
authors.initials: J
authors.lastname: Ahner
authors.forename: Paul M
authors.initials: PM
authors.lastname: Jones
authors.forename: Charanjit Singh
authors.initials: CS
authors.lastname: Bhatia
keywords: Curie temperature; filtered cathodic vacuum arc; heat-assisted magnetic recording; sp3 hybridization; thermal stability; ultrathin carbon