This award supports computational materials theory and education focused on microstructure evolution in ferromagnetic materials. As promising candidates for ultra-high density magnetic and magneto-optical recording media and for high energy product hard magnets in micro-electromechanical systems, iron-platinum films are attracting extensive experimental research. Microstructure engineering of iron-platinum films faces scientific and technological challenges to further improve their magnetic properties and meet the increasing requirements for high technology applications. The PI aims to establish microstructure property-mechanism relationships and find processing routes to produce the desired microstructures in iron-platinum films. The PI will develop phase field micromagnetic and microelastic models of iron-platinum films in combination with the models of ordering, decomposition, and grain growth to perform simulation studies of crystallographic microstructure formation and ferromagnetic domain evolution. The modeling will treat multiple physical processes during film annealing, including ordering transition, decomposition, grain growth, and simulate the formation of crystallographic microstructures. The magnetic properties of iron-platinum films with the obtained underlying microstructures will be further investigated by modeling and simulation of ferromagnetic domain evolution in the films. The objectives of this project are to (1) develop computational tools for simulating microstructure formation and magnetic domain evolution in iron-platinum films, (2) correlate processing, microstructures, and magnetic properties, (3) provide quantitative explanation of experimental findings, and (4) identify novel microstructures for improved magnetic properties and design appropriate processing to produce such microstructures. The PI also aims to provide insight into the microstructure engineering of other thin film ferromagnetic materials. The supported research and education will train a graduate student in computational materials science, and provide opportunities for undergraduate students to participate and gain experience in simulation-based materials research. Educational modules will be developed for classroom demonstration and hands-on virtual experiments for students. Educational materials will also be developed with an aim to engage high school students and teachers and to foster interest in Simulation-Based Science and Engineering. The PI commits herself to create opportunities for talented women and underrepresented minorities to participate in computational materials research.
NON-TECHNICAL SUMMARY:
This award supports computational materials theory and education focused on the magnetic properties of thin films. The research will focus on thin films composed of iron and platinum. Recent experiments suggest this material would be a promising candidate for data storage technologies. The PI aims to use computer simulation to model the structure of the material on length scales larger than an atom but much smaller than a thumb. Structure on this scale controls the magnetic properties of the material that make it suitable for recording technology applications. The PI will develop computational tools that will enable her to establish connections between the structure and properties of the material. Once these are understood, the research will focus on addressing how to actually make films with the right structure. The computational tools developed in this research project will advance computational materials science. The research focuses on a technologically important material and how to process it, further contributing to keeping America competitive. The supported research and education will train a graduate student in computational materials science, and provide opportunities for undergraduate students to participate and gain experience in simulation-based materials research. Educational modules will be developed for classroom demonstration and hands-on virtual experiments for students. Educational materials will also be developed with an aim to engage high school students and teachers and to foster interest in Simulation-Based Science and Engineering. The PI commits herself to create opportunities for talented women and underrepresented minorities to participate in computational materials research.
As promising candidates for ultra-high density magnetic and magneto-optical recording media and for high energy product hard magnets in micro-electromechanical systems, iron-platinum (FePt) films are attracting extensive attention. Being ferromagnetic system of multi-phase, multi-variant, and multi-domain, the magnetic properties strongly depend on the underlying crystallographic microstructure and the ferromagnetic domain evolution. The complexities in the microstructure and its relations to both processing and properties pose significant difficulties to experimental approach, while analytical approach is futile in many cases due to the complicated multiphysical processes which are largely controlled by long-range elastic/magnetic/electric interactions sensitively dependent on domain and microstructures. This project has developed a novel materials modeling for a systematic computational study of FePt films, which complements experimental investigations of this important magnetic material system to advance fundamental understanding of the magnetic properties and their further improvement to meet the increasing requirements for high technological applications. Intellectual Merit: Phase field micromagnetic and microelastic model in combination with the models of ordering and decomposition is developed. The model is employed to perform simulation studies of crystallographic microstructure formation under magnetic field during phase separation in FePt and in spinodal-type magnetic materials which provide guidance for microstructure engineering through magnetic annealing. The effects of microstructures, in particular, various types of crystal twin boundaries, on domain evolutions and magnetic properties are also investigated, which correlates microstructures and properties. To address electric current that plays important roles in domain switching of metallic magnetic materials, the model is further developed to include electrical conduction in complex microstructures and the effects of electric current on magnetic domain behaviors. The integrated model provides a unique capability to simulate magnetic domain phenomena in metallic magnetic materials of complex microstructures under magnetic, mechanical, and electric conditions. Moreover, new formulations in terms of 2D Fourier transform of the phase field variables in the film plane are developed to effectively solve image forces and magnetic/electric charges of free surfaces without involving empty space or iterative scheme. This drastically increases computational efficiency, allowing larger-scale simulations of microstructure formation and magnetic domain evolutions in planar magnetic thin films (both continuous and nanopatterned). This project has developed advanced phase field modeling of multi-phase multi-variant complex microstructure formation and the effects of microstructures on magnetic properties through domain evolutions, and offers effective computational tools for simulating FePt films to complement experimental investigations. Various magnetic materials have also been considered for comparison studies to advance fundamental scientific understanding of processing-microstructure-property relations. Broader Impact: The project has trained graduate students in computational materials science, and provided opportunities for undergraduate students to participate and gain experience in simulation-based materials research. The participating students include one woman graduate student and one Hispanic undergraduate. The outcomes have been reported in 12 refereed journal papers (five with graduate students as first authors), 12 oral and 2 poster presentations at TMS and MRS conferences (six by graduate students), 6 seminar presentations (one by graduate student), and 2 graduate research presentations (one received the First Place Award). The PI developed new graduate course "Materials Modeling of Phase Transformation and Microstructure Evolution" and received very positive feedback from students. The colorful visualization and animation of microstructures have been used as examples in the PI’s undergraduate and graduate courses. The research outcomes of this project have also been featured in presentations made to high school students and teachers to foster next-generation’s interest in Simulation-Based Science and Engineering, as part of campus visits and demonstrations, MTU’s Summer Youth Program, and MTU’s delivery of ASM Materials Camp for Teachers.
