Abstract
We perform first-principles calculations to predict the morphology of $L{1}_{0}$ ordered FePt nanoparticles grown on Mg(Ti)O substrates with relevance to application in heat-assisted magnetic recording (HAMR) media. We show how incorporation of Ti into MgO substrates reduces the FePt adhesion energy from $\ensuremath{-}1.29$ (pure MgO) to $\ensuremath{-}2.35\phantom{\rule{4pt}{0ex}}\mathrm{J}/{\mathrm{m}}^{2}$ (pure TiO). This effect is due to the formation of strong Fe-Ti bonds at the interface. Consistent with experimental observations, the predicted equilibrium morphology of supported FePt nanoparticles is significantly changed, corresponding to increased wetting. This behavior is undesirable for HAMR media since it promotes grain growth which limits the storage density. We show how passivation of surface Ti atoms (e.g., with MgO) is sufficient to restore the wetting observed for pure MgO substrates offering a viable strategy for optimization of next generation recording media.
Highlights
L10 ordered FePt exhibits high magnetrocrystalline anisotropy in the [001] direction (7 × 107 ergs/cm3) and is one of the preferred materials for heat-assisted magnetic recording (HAMR) media in hard disk drives (HDDs) [1,2]
The (001), (100), (110), (011), and (111) surface slabs contains 20, 20, 8, 10, and 10 atoms, respectively. 9 × 9 × 1 MP grids are used for the Brillouin zone (BZ) sampling with only 1 k point in the direction normal to the surface
FePt is strained by 10% in our calculation. In reality this large lattice mismatch would be partially relieved by formation of dislocations at the interface
Summary
L10 ordered FePt exhibits high magnetrocrystalline anisotropy in the [001] direction (7 × 107 ergs/cm3) and is one of the preferred materials for heat-assisted magnetic recording (HAMR) media in hard disk drives (HDDs) [1,2]. Increasing the storage density of HDDs further requires decreasing the physical dimensions of each bit which are currently limited by the FePt grain size [3]. Due to the good conductivity of MgTiO, this substrate is suitable for direct current (dc) sputtering which offers better control of the deposition rate and the FePt grain size. The increased wetting of FePt on MgTiO makes further reduction of grain size difficult and offsets any benefit obtained by the use of dc sputtering. The atomistic origin of the increased wetting on MgTiO is not understood, presenting an obstacle to further optimization of FePt/MgTiO HAMR media
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
