Development of Novel Simulation Tools for Lubricants / Overcoats / ABS Design in HAMR Technology

[01] Front matter a. Date: 04/28/2011 b. Abstract As heat assisted magnetic recording (HAMR) systems are set to be commercialized in the very near future, head disk interface (HDI) research focusing on the reliability and mechanical integration become the major technical barriers to be resolved [1]. To select the optimal HDI materials and configuration for HAMR among the enormous number of candidates for lubricant / overcoat systems, we need to fully understand multiscale phenomena containing numerous combinatorial complexities of highly interactive layers as well as consider various environmental parameters such as repeating thermal stress cycles, while maintaining the integrity of the corrosion protection. Current experimental and theoretical methods are limited in synthesizing materials and systems due to the extremely large set of decision parameters. Much effort and time must be applied to fully explore the combinatorial possibilities of composite HDI materials. In this proposal, we plan to examine HDI in HAMR through multiscale simulations which will holistically integrate lubricants, overcoats, and air bearing system (ABS) in non-isothermal conditions, and further provide the optimal design criteria for HDI modeling to obtain the best performance. We will first elucidate the mechanisms underlying the critical issues in HDI with conventional lubricants and overcoats (i.e., lubricant adsorption / desorption, evaporation, and degradation). We will then propose a novel overcoat known as graphene which has superior thermal and mechanical properties with a single atomic layer thickness that could potentially double the areal density without changing any specs. Innovative candidates for lubricant systems (hybrids of perfluoropolyethers (PFPEs) and carbon nanotube (CNT) or fullerene) and a �“buffer layer�” concept, ideal for tuning the adhesion and self healing properties will be explored. The interaction between graphene or other custom designed overcoats and lubricants at high temperature conditions will be examined at atomistic and molecular level simulations. Mesoscale level theory will be incorporated with pairings of novel lubricant / overcoat systems providing an innovative ABS design criteria under harsh environments operating in high temperature gradients. Our simulation result can be coupled with sponsor�’s experimental data, or student internships can be used to assist in measurements, to facilitate synergy. c. Proponent(s) and affiliation(s): Myung S. Jhon, Professor, Department of Chemical Engineering and Data Storage Systems Center Carnegie Mellon University, Pittsburgh, PA 15213 mj3a@andrew.cmu.edu d. Designated contact person: Yiao-Tee Hsia

yiao-tee.hsia@wdc.com

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[02] Subject of research and relevance to issue(s) to be solved.

a. Complete description of the research matter and its connection with ASTC stated goals

In this proposal, we aim to develop a holistically integrated model of the HDI system via a multiscale / multiphenomena approach to synthesize novel lubricant and overcoat materials and systems which can be used for HAMR technology with a goal of achieving recording densities over 4 TB/in2 and an operating temperature of approximately 400-550 C. Conventional HDI configuration is inadequate in HAMR as the repeating thermal stresses cause serious defects including adsorption / desorption, evaporation, and degradation of lubricant film as well as instability in the fly height of the head operation in ABS under laser induced protrusion [2]. Also, the system may require novel lubricant / overcoat systems, which effectively protect the corrosion, retain the affinity between layers, and influence the thermal transport to the lubricant layer in high temperature stress. However, thermal and mechanical properties of thin film layers are highly anisotropic due to their huge aspect ratio with nanoscale thickness making it computationally intensive. In addition, the nanoscale / high temperature system is very difficult to systematically reform experimentally. The development of rigorous design criteria for these types of systems requires trial and error procedures with the enormous amount of combinatorial variables. Our proposed holistic model can successfully handle the solution either by a direct or inverse approach. The proposed integrated multiscale simulation, will enable the efficient and realistic modeling of integrated HDI with seamless solutions for the combinatorial problems faced in the HAMR system. Consistent with ASTC goals, we will explore a novel graphene overcoat, which is an exceptionally thin material with the potential to double areal density without changing any other specs, and investigate innovative lubricant systems including the concept of a buffer layer with combinations of PFPEs and CNT or fullerene. In ABS design, fly height dependence on the air sticking coefficient with lubricant as well as its temperature dependence will be addressed to target a clearance of less than 1nm. b. Proposed research approach(es) - computational

In this proposal, novel HDI systems and the multiscale simulation strategies will be developed focusing on the combinatorial problems with various essential environmental variables as well as design of novel HDI configuration in the HAMR system. Here, we introduce the technical barriers in HAMR and the strategies in our multiscale framework for providing a better HDI design below.

i) What is required for HDI research in HAMR?

The success of HAMR with its harsh operating conditions requires paradigm shifting design of HDI to make it marketable [3]. With HAMR media being heated to

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temperatures of 400-550 C, currently popular lubricants such as Zdol or blends of various lubricants may not be suitable for HAMR applications. In addition, molecular weight and its distribution play a critical role in controlling adsorption / desorption kinetics and evaporation, and endgroups in PFPE undergo thermal oxidative degradation at elevated temperature [4]. Therefore, the investigation of novel HDI including robust lubricants with desirable pairs of multiple functional groups as well as a new overcoat such as graphene are required for HAMR operation. In this proposal, we will develop holistic integrated simulation tools with novel lubricants / overcoat / ABS to overcome these technological barriers. Our methodology will range from atomistic to continuum scales in a middle-out approach (Fig. 1). We will now illustrate our integrated multiscale approach and component level description as well as our unique simulation capability and highlight our previous achievements relevant to HAMR technology.

Figure 1. Current approach and proposed multiscale integration in HDI of HAMR for reliable design in a high temperature environment [5, 6].

ii) Why do we need holistic integration of multiscale modeling in HAMR?

HDI is a hierarchical system with interacting sub-components. Existing modeling techniques for individual scales lack communication between components, which may lead to inaccurate prediction of the properties, especially at high temperature conditions. Therefore, a holistic approach with seamless integration is the next step to develop

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realistic models to accurately capture all the essential features. In this respect, we have recently developed a fundamental framework and several scenarios on multiscale modeling with optimization [5].

We have thus far examined multiscale methodologies for atomistic / molecular simulations for lubricants and overcoats as well as lattice Boltzmann method (LBM) for mesocale ABS modeling at isothermal condition [6]. During this project period, our efforts will thoroughly span atomistic / molecular model integration, and further proceed toward continuum simulation to fully integrate the HDI in the HAMR system. The entire modeling scheme will be conducted in a non-isothermal environment.

iii) Innovative overcoat and lubricant/buffer systems

Despite the single atomic thickness, the superior mechanical properties of graphene motivate active research for its applications [7, 8]. Therefore, graphene can be a promising candidate for the overcoat with potential to double areal density without changing any other specs. Graphene has a nature of lateral thermal transport, which can be incorporated to reduce the acute thermal effects on the lubricant layer due to the hotspot, yet it is currently difficult to produce in large size wafers without defects. We will particularly focus on mechanical and thermal properties in the presence of grain boundaries. By using molecular dynamics (MD), we initially characterized the mechanical strength of graphene in the presence of defects (grain boundary) by systematically varying temperature (Fig. 2). We will further examine the mechanical properties of multiple graphene layers as well as anisotropic thermal effects with the grain boundary condition. Our previous nanoscale multilayer heat transfer simulations with LBM can be incorporated to predict meso / macroscale heat transport phenomena. Also, the stability and affinity of lubricants and overcoats, which provide the key parameters for achieving good protection of the magnetic layer in HAMR system, will be specifically focused.

Figure 2. Thermal effect on the graphene structures with defects: (a) at low and (b) high temperatures.

In addition to the graphene application in the overcoat area, we will introduce new HDI designs consisting of buffer / lubricant layers (i.e., graphene / CNT or fullerene /

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lubricant systems) as potential candidates for HDI configurations (Fig. 3). Combined with the graphene layer, buffer materials such as CNT or fullerene are solid state bearings [9, 10], which could further reduce the wear phenomena in nanoscale mechanical devices (NEMS). For HDI in HAMR, the contact and collision of the head can be a critical issue due to the effect of laser protrusion on ABS. Therefore, our new HDI design accommodates the combination of PFPE lubricants for protection from collision damage. Molecular interaction between a variety of PFPEs, CNT, and fullerene with graphene will be carefully examined to find optimal candidate pairs of lubricant and overcoat systems. We will discuss evaluating the proposed novel lubricant/overcoat materials in detail in the following section.

Figure 3. Designs of conventional and our proposed novel HDI for HAMR technology: (a) conventional HDI, (b) HDI with liquid (i.e., PFPEs) or solid (i.e., CNT or fullerene) state lubricants and graphene overcoats, (c) HDI with hybridization of lubricants and fullerene, and (d) stick-slip rolling model with a step rotation of a fullerene molecule on the graphene [9].

iv) Focuses on atomistic / molecular simulations for lubricant and overcoat.

In order to find stable and robust lubricants for HAMR, atomistic mechanisms of lubricant adsorption / desorption on the overcoat and degradation phenomena have to be understood via atomistic models. In our preliminary studies, we examined the interactions among functional groups and overcoats by using quantum mechanics (i.e., ab initio calculation) [11]. We obtained preliminary results with graphene as an alternative candidate for the HAMR overcoat (Fig. 4) due to its thermal and mechanical endurance. For molecular / mesoscale phenomena in conditions with periodic high temperature stress, the response of lubricants on the overcoats will be investigated by hybridizing atomistic simulation with atomistic scale / coarse-grained MD models which we have developed for thin PFPE films up to monolayer thickness during the past decade [13-17]. We will select the optimal lubricant / overcoat pairings by optimizing the adhesion to the surface while also maximizing the self-healing ability of lubricants. This may require evaluating various blends of conventional lubricants such as Ztetraol multidentate (ZTMD; Ztetraol based PFPE with additional hydroxyl functional adsorption sites at the center of the chain) and A20H (PFPE with benzene rings, which enables stronger interaction with overcoats but with less mobility). The molecular weight distribution and thermal depolymerization reaction of endgroup degradation will also be carefully examined to

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find optimal atomistic/molecular structure with thermal stability. Furthermore, we will design novel carbon hybrid materials to further improve lubricant-overcoat interaction. The buffer layer on top of graphene will be probed to provide high flexibility in HDI design. Other possible scenarios include CNT or fullerene as the sole lubricant on graphene surface. Hence, our simulation tools provide us the opportunity for atomistic architecture at a level, where the experimental methods are not feasible due to the extensive numbers of parameters in this combinatorial problem. This will then lead us to precisely transfer molecular parameters such as surface morphology to mesoscale level simulations for ABS modeling as introduced below.

Figure 4. A composite interaction zone of PFPE-PFPE and multilayer graphene system.[make smaller]

v) Non-isothermal, mesoscale modeling approach in ABS design

Current industrial ABS design fundamentals are based on the modified Reynolds equation (MRE), originated from Burgdorfer [19], Hsia & Domoto [20], and later rigorously derived from the Boltzmann transport equation (BTE), pioneered by Fukui and Kaneko [21], and completed by Kang, Crone, and Jhon [22]. The difficulties in this type of simulation are incorporating molecular scale properties originating from lubricant behavior as well as the incorporation of non-isothermal effects critical to HAMR

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technology. In other words, substantial modification to our knowledge base must be made in MRE to accurately model ABS for HAMR. To overcome these stumbling blocks, we have developed a novel LBM to simulate ABS in the non-isothermal condition. LBM is an extensive simulation tool with a simple algorithm, which enables us to hybridize multiple physical phenomena including molecular level information and is ideal for parallel computation. Although it stems from BTE, LBM enjoys computational advantages since it can be interpreted as a rule based algorithm and additional physics are easy to incorporate. With these advantages, we will explicitly analyze ABS dynamics under thermal fly height control and laser induced protrusion in HAMR by incorporating the thermal LBM model [23]. By constructing an integrated model including molecular models, we intend to incorporate specifically both lube pick-up and nanoscale heat transfer mechanisms, which will capture realistic and accurate physics in HDI and provide the criteria for advanced ABS design. Especially, we will consider the effect of the sticking coefficient of air molecules with lubricant on fly height. The mesoscale modeling developments will be linked to the system level optimization in the future.

vi) Our highlighted achievements in developing simulation methods so far

During the past decade, we have developed numerous simulation techniques over various scales appropriate for individual sub-component technology in HDI (i.e., atomistic & molecular scale for overcoats & lubricants, mesoscale for ABS, and system design). Here, we propose holistic integration of multiscale system modeling, which is especially effective for the condition-sensitive systems such as HAMR. To demonstrate our capability, we introduce our highlighted efforts relating to multiscale modeling by summarizing our earlier achievement of performing large scale simulations relevant to HAMR technology.

Atomistic scale:

By using quantum mechanical calculations (ab initio), we investigated force field parameters of lubricants, based on explicitly modeled atoms of functional PFPEs in isothermal condition. From intra-molecular force-field parameters, we found the effects of the electronegativity difference on different types of bonds and transferability of force constants between similar types of PFPEs (Fig. 5 (a)) [11]. Inter-molecular interaction energies between lubricants quantitatively elucidated the existence of hydrogen bonding between the hydroxylated functional endgroups (Fig. 5 (b)). We also observed reduction of the inter-molecular interaction when blending hydroxylated and non-hydroxylated groups where hydrogen bonding effects are not present. These observations indicate the capability of molecular tuning on lubricant behavior could be accomplished via blending to obtain desired mechanisms in the lubricant system. In addition to the lubricant

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interactions with various conventional overcoats (i.e., amorphous, nitrogenated, and hydrogenated carbons), we also delved into the interaction among PFPEs and novel overcoat material such as graphene (Fig. 5 (c)), for the first time, to shed light on its viability for future HDD applications. We developed potential energy parameters that have been utilized as an input for the molecular scale models.

Figure 5. Quantum mechanical models used in simulations of (a) intra-molecular interactions, (b) interaction between PFPEs, and (c) between PFPE and graphene.

Molecular scale:

We have made several original contributions and accumulated extensive know-how in developing MD methodologies and investigated the physiochemical properties of PFPE thin films in the nanoscale regime by introducing a coarse-grained, bead-spring model, which simplifies the chemical structures of PFPEs while retaining the essential physics of the molecular system. This model has been developed to utilize atomistic information from the quantum mechanical calculations. Our MD simulations were developed to characterize nanoscale thin films of PFPEs with the static and dynamic properties over a broad range of temperatures and further utilized to introduce novel lubricant systems. We examined equilibrated surface morphologies, where the dependences on the nanoscopic architecture and film thickness were studied by correlating the surface morphology parameters with the transport properties (Fig. 6 (a)) [24]. We also found that the diffusion coefficient (D) of PFPEs becomes anisotropic in nanoscale film thickness due to the surface interaction (Fig. 6 (b)) by observing perpendicular and parallel components [25].

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Analogous to the HDI system, �“compression�” and �“tension�” of lubricant films were simulated by moving the top surface towards and away, respectively, from the bottom surface (Fig. 6 (c)) [26]. A hysteresis loop in the film normal stress profile was observed for the first time, indicating the existence of PFPE viscoelasticity (Fig. 6 (d)). By using non-equilibrium MD, we developed our nanorheology modeling method for the first time to implement the lubricant surface during take-off and landing processes [27]. The calculation results from various MD methodologies were verified via the experiments to hybridize with ABS.

Figure 6. (a) surface morphology analysis, (b) anisotropy of diffusion coefficient (D|| and D are the diffusion coefficients of parallel and perpendicular directions, respectively), (c) mechanical stress on PFPEs by using �“compression�” and �“tension�” processes, (d) and the hysteresis of normal stress during �“compression�” and �“tension�”.

We characterized the molecular properties of various conventional and new types of PFPE films on the variety of overcoat (i.e., amorphous, nitrogenated, and hydrogenated carbons) [28]. Here, we confirmed that the hydroxyl endgroups are located on the surface, which represents the functional PFPE molecules are anchored on the surface with strong functional bead and surface interaction (Fig. 7 (a)). Additional peaks were found in the A20H and ZTMD, where the majority of functional beads are entirely located on the surface so that a few functional beads are thrust away from the surface. ZTMD exhibits narrow distribution with the peak on the smallest radius of gyration (Rgz) (Fig. 7 (b))

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while it shows less diffusivity than other PFPEs (Fig. 7 (c)). By introducing the functional groups in the chain center, ZTMD forms additional anchors at the center and adhesive interaction with the disk surface increases to achieve very low film thickness in HDI. Both advantageous mobility and desirable film conformation cannot be simultaneously obtained from the single component PFPEs. Therefore, we introduced the concept of blending different types of PFPEs, which may enable us to obtain the advantages from each component [29]. We examined the blend of non-functional and functional PFPEs (Fig. 7 (d)). Here, we found that nano blending is capable of providing the desirable film conformation as well as mobility, which are suitable for HDI in harsh conditions.

Figure 7. Characterization of Zdol, Mono, A20H, and ZTMD: (a) endbead density profiles, (b) distributions of perpendicular component Rgz, and (c) mean-square displacements (MSD). (d): Side views of binary mixture (Z and ZTMD) with various volume fraction of ZTMD ( ZTMD).

Mesoscale:

We previously developed the air bearing code using finite element method, which was widely used for ABS design at industrial manufacturers such as IBM, Seagate, and Western Digital. One example of our slider design and pressure contour based on our

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code is illustrated in Figs. 8 (a) & (b). Our code had the advantage of using the accurate database obtained from BTE and handled transient phenomena, yet produced inaccurate results in the large Knudsen number (Kn) case. MRE, which stemmed from the database, has limitations in incorporating accurate coupling between microscopic phenomena such as lubricant behavior. A novel LBM, which is more efficient than the conventional computational fluid dynamics and easy to hybridize with other physical phenomena, was then developed to model the ABS (Figs. 8 (c) & (d)) [30]. To facilitate the general geometry handling capabilities, the Taylor series expansion and least squares based LBM (TLLBM) was employed to simulate the flow conditions under a model slider. Truncated power-law and Bird-Carreau models were incorporated to capture the non-Newtonian behavior of ultra-thin lubricant film undergoing extremely high shear rates by modifying the relaxation time as a function of shear rate. We completed several benchmark studies with single flow field analysis under the model slider for different constitutive relationships. In the high Kn flow analysis of ABS, the slip boundary model is very important to guarantee the accuracy of the solution. The Langmuir slip model for the rarified gas flow was incorporated and its feasibility and accuracy was examined in nanoscale flow simulations [31]. Thus, LBM will be used for the holistic integration model instead of MRE.

Figure 8. (a) Slider design and (b) pressure contour based on our ABS code. (c) Simplified HDI structure and (d) its normal pressure and shear stress profiles.

c. Likely outcome of research

Our project will provide a robust holistic multiscale simulation tool with a novel development of the lubricant / overcoat / ABS system used in HAMR. Specifically,

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atomistic and molecular dynamic simulation tools to examine physiochemical characteristics of lubricants and overcoats at an elevated temperature will be performed. From this approach, we will overhaul conventional lubricants and overcoats, and tailored HDI designed from a molecular level will be delivered for HAMR systems. One of our primary goals is to deliver the best corrosion protection barriers for the magnetic layer in non-isothermal conditions with high peak temperature. The outcome will also include the stability of lubricants in repeating ramps of thermal stress and affinity between layers. Graphene as a overcoat will be an innovative challenge for future HDI design beyond HAMR. One of most complex simulations using combinatorial multiscale approaches is the graphene / fullerene or CNT / lubricant hybrid system to optimize adhesion and self-healing properties. The capability of analyzing vast amounts of information will make our simulation techniques useful tools for determining design and selection criteria in developing the best systems and materials in HAMR HDI. In addition, the novel mesoscale model will be hybridized into these molecular level theories to analyze and develop ABS under thermal fly height control and laser induced protrusion, targeting an advanced design with less than 1nm dynamic clearance capable of exceeding 4 TB/in2 recording densities, thus meeting ASTC�’s target. Multi-physics in this integrated model will initiate vigorous interactions among the experimental research groups in ASTC. The developed model here will be used in the optimization of future HDI progress beyond current feasible designs.

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Fatih Erden, �“Heat Assisted Magnetic Recording,�” P. IEEE, 96, 1810 (2008). 2. Y. Ma and B. Liu, �“Lube Depletion Caused by Thermal-desorption in Heat Assisted Magnetic

Recording,�” IEEE Trans. Magn., 44, 3691 (2008). 3. J. Zhang, R. Ji, J.W. Xu, J.K.P. Ng, B.X. Xu, S.B. Hu, H.X. Yuan, and S.N. Piramanayagam,

�“Lubrication for Heat-assisted Magnetic Recording Media,�” IEEE Trans. Magn., 42, 2546 (2006). 4. L. Wu, �“Modelling and Simulation of the Lubricant Depletion Process induced by Laser Heating in

Heat-assisted Magnetic Recording System,�” Nanotechnology, 18, 215702 (2007). 5. P.S. Chung, M.S. Jhon, and L.T. Biegler, �“The Holistic Strategy in Multi-scale Modeling,�” Adv. Chem.

Eng., 40, 59 (2011). 6. M.S. Jhon, R. Smith, S.H. Vemuri, P.S. Chung, D. Kim, and L.T. Biegler, �“Hierarchical Multiscale

Modeling Method for Head/disk Interface,�” IEEE Trans. Magn., 47, 87 (2011). 7. C. Lee, Q. Li, W. Kalb, X.-Z. Liu, H. Berger, R.W. Carpick, and J. Hone, �“Frictional Characteristics of

Atomically Thin Sheets,�” Science, 328, 76 (2010). 8. R. Guerra, U. Tartaglino, A. Vanossi, and E. Tosatti, �“Ballistic Nanofriction,�” Nat. Mater., 9, 634

(2010). 9. K. Miura, S. Kamiya, and N. Sasaki, �“C60 Molecular Bearings,�” Phys. Rev. Letts., 90, 055509 (2003). 10. M. Lucas, X. Zhang, I Palaci, C. Klinke, E. Tosatti, and E. Riedo, �“Hindered Rolling and Friction

Anisotropy in Supported Carbon Nanotubes,�” Nat. Mater., 8, 876 (2009). 11. R. Smith, P.S. Chung, J.A. Steckel, M.S. Jhon, and L.T. Biegler, �“Force field parameter estimation of

functional perfluoropolyether lubricants,�” J. Appl. Phys., 109, 7B728 (2011). 12. J. Kong, C.A. White, A.I. Krylov, D. Sherrill, R.D. Adamson, T.R. Furlani, M.S. Lee, A.M. Lee, S.R.

Gwaltney, T.R. Adams, C. Ochsenfeld, A.T.B. Gilbert, G.S. Kedziora, V.A. Rassolov, D.R. Maurice, N. Nair, Y. Shao, N.A. Besley, P.E. Maslen, J.P. Dombroski, H. Daschel, W. Zhang, P.P. Korambath, J. Baker, E.F.C. Byrd, T.V. Voorthis, M. Oumi, S. Hirata, C.-P. Hsu, N. Ishikawa, J. Florian, A. Warshel, B.G. Johnson, P.M.W. Gill, M. Head-Gordon, and J.A. Pople, �“Q-Chem 2.0: A High-performance ab initio Electronic Structure Program Package,�” J. Comp. Chem., 21, 1532 (2000).

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13. X. Ma, C.L. Bauer, M.S. Jhon, J. Gui, and B. Marchon, B., �“Monte Carlo Simulations of Liquid Spreading on a Solid Surface: Effect of End-group Functionality,�” Phys. Rev. E, 60, 5795 (1999).

14. S. Izumisawa and M.S. Jhon, �“Molecular Simulation of Thin Polymer Films with Functional Endgroups,�” J. Chem. Phys., 117, 3972 (2002).

15. Q. Guo, S. Izumisawa, M.S. Jhon, and Y.T. Hsia, �“Transport Properties of Nanoscale Lubricant Films,�” IEEE Trans. Magn., 40, 3177 (2004).

16. Y.T. Hsia, Q. Guo, S. Izumisawa, and M.S. Jhon, �“The Dynamic Behavior of Ultrathin Lubricant Films,�” Microsyst. Technol., 11, 881 (2005).

17. P.S. Chung, H. Park, and M.S. Jhon, �“The Static and Dynamic Responses of Binary Mixture Perfluoropolyether Lubricant Films �– Molecular Structural Effects,�” IEEE Trans. Magn., 45, 3644 (2009).

18. W.T. Kim, D. Kim, S.H. Vemuri, S.-C. Kang, P.S. Chung, and M.S. Jhon, �“Multi-component Gas Mixture Air Bearing Modeling via Lattice Boltzmann Method,�” J. Appl. Phys., 109, 07B759 (2011).

19. A. Burgdorfer, �“The Influence of the Molecular Mean Free Path on the Performance of Hydrodynamic Gas Lubricated Bearings,�” J. Basic Eng., 81, 94 (1959).

20. Y.T. Hsia and G.A. Domoto, �“An Experimental Investigation of Molecular Rarefaction Effects in Gas Lubricated Bearings at Ultra Low Clearance,�” ASME J. Lub. Tech., 105, 120 (1983).

21. S. Fukui and R. Kaneko, �“Analysis of Ultra-Thin Gas Film Lubrication Based on the Linearized Boltzmann Equation (Influence of Accommodation Coefficient),�” JSME Int. J., 30, 1660 (1987).

22. S.-C. Kang, R.M. Crone, and M.S. Jhon, �“A New Molecular Gas Lubrication Theory Suitable for Head-Disk Interface Modeling,�” J. Appl. Phys., 85, 5594 (1999).

23. S.S. Ghai, W.T. Kim, C.H. Amon, and M.S. Jhon, �“Transient Thermal Modeling of a Nanoscale Hot Spot in Multilayer Film,�” J. Appl. Phys., 99, 08F906 (2006).

24. Q. Guo, H. Chen, W.T. Kim, and M.S. Jhon, �“Novel Multiscale Modeling and its Application to Integrated Head Disk Interface Simulation,�” J. Appl. Phys., 97, 10P310 (2005).

25. M.S. Jhon, S. Izumisawa, Q. Guo, D.M. Phillips, and Y.T. Hsia, �“Simulation of Nanostructured Lubricant Films,�” IEEE Trans. Magn., 39, 754 (2003).

26. Q. Guo, P.S. Chung, and M.S. Jhon, �“Nano-mechanics of Perfluoropolyether Films: Compression versus Tension,�” IEEE Trans. Magn., 44, 3698 (2008).

27. Q. Guo, P.S. Chung, M.S. Jhon, and H.J. Choi, �“Nano-rheology of Single Unentangled Polymeric Lubricant Films,�” Macromol. Theor. Simul., 17, 454 (2008).

28. H. Chen, Q. Guo, and M.S. Jhon, �“Effects of Molecular Structure on the Conformation and Dynamics of Perfluoropolyether Nanofilms,�” IEEE Trans. Magn., 43, 2247 (2007).

29. P.S. Chung, H. Chen, and M.S. Jhon, �“Molecular Dynamics Simulation of Binary Mixture Lubricant Films,�” J. Appl. Phys., 103, 07F526 (2008).

30. D. Kim, W.T. Kim, H.M. Kim, H. Chen, P. Jain, and M.S. Jhon, �“A Novel Simulation of Air/liquid Bearing based on Lattice Boltzmann Method,�” J. Appl. Phys., 105, 07B701 (2009).

31. H.M. Kim, D. Kim, W.T. Kim, P.S. Chung, and M.S. Jhon, �“Langmuir Slip Model for Air Bearing Simulation using the Lattice Boltzmann Method,�” IEEE Trans. Magn., 43, 2244 (2007).

[3] Resources required to perform project

a. Personnel, students, etc.: One full-time graduate student

b. Equipment, lab, etc.: Upgrading computing facilities

c. Computational: Software upgrade

[4] Resources other than ASTC funding to perform project

a. Grants: N.A

b. Contracts: N.A

c. Other: N.A

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[5] Resources requested from ASTC and how they will be utilized

a. funding

ITEM JUSTIFICATION BASE TOTAL i. Overhead Facilities and Administration:

Overhead on this proposal has been calculated at our current proposed or negotiated non-federal rate for all fiscal years. The modified total direct cost base (MTDC) amount used in calculating the indirect costs is the total direct costs, excluding equipment, capital expenditures, charges for tuition remission, rental costs, scholarships and fellowships, internally charged telephone, internally charged copying, and individual subcontract costs in excess of $25,000. The current non-federal rate is 63%.

63% of $33,820 (MTDC)

$21,307

ii. Direct Project Cost Technical Supplies and Services: This includes costs incurred to maintain and repair equipment used solely by the project as well as specialized equipment owned by a laboratory and used by the project; Lab/data supplies or technical items that are considered to be expendable, as well as, non-capital equipment items with a purchase price of less than $1,000 per item; Cleanroom fees (Nanofabrication Facility) for growth and fabrication equipment housed in a central laboratory where users must pay a fee to gain access to the facility and for use of equipment in the facility; Software licensing, maintenance and support. Publication/Documentation/Dissemination: Costs of documenting, preparing, publishing, disseminating and sharing research findings and supporting material; page charges for professional scientific and engineering journal publications. Computing Facility Fees: The Carnegie Institute of Technology (College of Engineering) maintains its own computing facility and is not dependent on the university maintained facility. Included in the support cost

$ 500 $ 1,000 $ 2,000

$ 3,500

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of our facilities are the costs associated with networking, systems software support, time-shared machines, printing, maintenance contracts, and salaries of the facility staff, including computer operators, systems programmers, systems engineers, line technicians, and repair technicians. Facilities maintenance costs for the PI�’s projects were derived from a comparison of Computing Facilities Support expenditures to research salaries and fringe benefits.

iii. Facility use fees N/A $ 0 iv. Materials N/A $ 0 v. Student Stipend/

Tuition Graduate Student Support: Stipend and tuition amounts are based on FY 2012 proposed rates. Graduate support is increased effective September 1. The colleges each set their graduate support rates in consultation with their faculty, department heads, deans and the Provost taking into account an evaluation of our historical market position in comparison to our peer institutions. Salaries for graduate students are based on a nine month academic year and three summer months. We are requesting one year of full tuition and stipend support for one graduate student researcher.

Stipend: $2,360×12 mos = $28,320 Tuition/fee: Full Academic Year support (9 mos) = $37,950

$66,270

vi. Travel Domestic Travel: Travel will include attendance by the PI at ASTC/sponsor specific meetings. Educational Institutions are not subject to the Federal Civilian Employee and Contractor Travel Expense Act of 1985 (Pub. L. 99-234) at this time. Costs incurred for travel, including lodging and other subsistence, will be considered reasonable and allowable to the extent that they do not exceed charges normally allowed by the University in its regular operations according to institutional policy. In the absence on institutional policy, the GSA rates shall apply.

2 west coast trips @ $1,000 per trip

$ 2,000

TOTAL REQUESTED

$93,077

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b. Expected technical cooperation with sponsor(s): materials to be provided by sponsor(s) (e.g., targets, devices, engineering support, etc.)

After establishment of the holistic integration model, the proprietary information on the lubricants for the input to our simulations is requested in our proposal. However, we may not need graphene and ABS information from the sponsors. Upon the success of the combinatorial research on lubricant / overcoat pairs, it would be desirable to have extensive discussion on material synthesis with sponsors.

c. Sponsors’ facility utilization

If available, access to experimental results is desirable to compare with our simulation results. Regular technical meetings with our sponsor to accurately plan our project are desirable.

d. Expected students’ internships

If appropriate, the student, who performs the simulation, could spend one-third of his time in the sponsor�’s lab to perform experiments and deliver simulation methodologies as well as to enhance university/industry collaboration.

[6] Time line

Time Period Milestone 6/1 (2011) �– 9/30 Lubricant modeling (atomistic / molecular)

10/1 �– 12/31 Alternative carbon overcoat modeling including graphene (Heat transfer / mechanical properties)

1/1 (2012) �– 2/29 Lubricant / carbon overcoat modeling (graphene) �– hybrid lubricants

3/1 �– 4/30 Lubricant / carbon overcoat / ABS modeling �– including buffer layer

5/1 �– 5/31 Report & holistic integration scenarios

[7] Not more than one page: Home institutions & resources

The PI has access to excellent computing facilities including 64 parallel processors with the state-of-the-art computing software, which are capable of calculating atomistic / MD, Monte Carlo (MC) simulation, and LBM. In addition, he has access to state-of-the-art interior point optimization algorithm, IPOPT. These computing supports, which are massively parallel computing network with enormous software resources, will lead to an extremely large database and large combinatorial integration models will be possible.

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Extensive collaboration among DSSC and their affiliated members, the PI can explore collaboration with experimentalists and manufacturers..

[8] Not more than one-half page per contributor: contact information and biographical sketch of researcher.

Dr. Myung S. Jhon, the PI for this project, is a Professor of Chemical Engineering and a member of the Data Storage Systems Center (DSSC) at Carnegie Mellon University in Pittsburgh, PA. He received his B.S. in Physics from Seoul National University, Korea, and his Ph.D. in Physics from the University of Chicago. He has served as visiting professor in several institutions, including the Department of Energy (National Energy Technology Laboratory and Sandia National Laboratories); UC Berkeley; IBM Research Center; and the Naval Research Laboratory. During his recent leave of absence, he also served as the President & CEO of Doosan DND Co., Ltd. He has contributed 740 publications (431 refereed publications and 309 technical reports) in the areas of computational methods (multiscale simulation, LBM, finite difference method, finite element method, MC, MD simulation, quantum simulation, optimization, and parallel computing), data storage systems, nanotechnology, fuel cells, equilibrium and non-equilibrium statistical mechanics, nucleation, fluid and solid mechanics, interfacial dynamics, polymer engineering, rheology, multiphase flow, tribology, chemical kinetics, organic light emitting devices, and chemical mechanical polishing equipment. He has organized eight U.S.-Korea Forums on a broad spectrum of nanotechnology related topics covering nano-electronics, education, nano-manufacturing, policy, nano-energy dealing with sustainability, and nano-biotechnology (http://www.andrew.cmu.edu/ org/nanotechnology-forum/). His research interests in nanotechnology deal with head-disk interface design for the DSSC, where he has made several technological contributions to the data storage industries including novel ABS and lubricant designs as well as applications dealing with novel functional materials such as graphenes, CNT, and PFPEs. He has won a number of teaching and research recognition awards, including the Ladd, Teare, Ryan, Dowd, and Li awards. His contact information is given as: Myung S. Jhon, Professor, Department of Chemical Engineering and DSSC Carnegie Mellon University, Pittsburgh, PA 15213 Phone: 412-268-2233

Email: mj3a@andrew.cmu.edu

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