Abstract
The challenges in designing future head disk interface (HDI) demand efficient theoretical modeling tools with flexibility in investigating various combinations of perfluoropolyether (PFPE) and carbon overcoat (COC) materials. For broad range of time and length scales, we developed multiscale/multiphysical modeling approach, which can bring paradigm-shifting improvements in advanced HDI design. In this paper, we introduce our multiscale modeling methodology with an effective strategic framework for the HDI system. Our multiscale methodology in this paper adopts a bottom to top approach beginning with the high-resolution modeling, which describes the intramolecular/intermolecular PFPE-COC degrees of freedom governing the functional oligomeric molecular conformations on the carbon surfaces. By introducing methodology for integrating atomistic/molecular/mesoscale levels via coarse-graining procedures, we investigated static and dynamic properties of PFPE-COC combinations with various molecular architectures. By bridging the atomistic and molecular scales, we are able to systematically incorporate first-principle physics into molecular models, thereby demonstrating a pathway for designing materials based on molecular architecture. We also discussed future materials (e.g., graphene for COC, star-like PFPEs) and systems (e.g., heat-assisted magnetic recording (HAMR)) with higher scale modeling methodology, which enables the incorporation of molecular/mesoscale information into the continuum scale models.
Highlights
The continuous increase in the areal recording density specification beyond 1 Tb/in2 has led to ever decreasing head media spacing (HMS) requirements at the head disk interface (HDI)
We have described a multiscale framework for modeling HDI materials
Beginning with the atomistic scale, we investigated the effect of detailed atomistic architecture on intramolecular and intermolecular PFPE degrees of freedom
Summary
The continuous increase in the areal recording density specification beyond 1 Tb/in has led to ever decreasing head media spacing (HMS) requirements at the head disk interface (HDI). In the inverse approach (bottom to top), the detailed, highresolution descriptions are constructed first, and via coarsegraining procedures, the outputs from the model are inputs for the development of lower resolution descriptions This multiscale integration style is useful in impacting device performance via nanoscale materials science and engineering, since the molecular architecture is at the root of material properties. By bridging the two scales, we are able to systematically incorporate first-principle physics into molecular models, thereby demonstrating a pathway for designing materials based on molecular architecture This approach allows us to describe the conformations, dynamics, morphology, rheology, and thermal performance of HDI materials. The atomistic review is followed by a survey of works investigating the HDI at the molecular/mesoscale via molecular dynamics simulations This is followed by an overview of novel integration methods and a discussion of the perceived impact of multiscale modeling on the challenges facing advanced HDI design
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