Electrochemical Synthesis of Structurally Ordered, Magnetic Pt-Based Alloys for Magnetic Microdevices

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TECHNICAL SUMMARY:The integration of hard magnetic materials within microfabrication processes may lead to novel devices with improved functionalities, such as novel storage media concepts or more effective magnetic microactuators. Electroplating methods would facilitate the fabrication of these structures by using purely additive processes, while allowing accurate reproduction of lithographic patterns. This research seeks to achieve a fundamental understanding of the growth and annealing process of electroplated, equiatomic Fe-Pt alloys, in order to produce materials useful in magnetic microsystems applications. Specifically, structurally ordered Fe-Pt films, micro- and nanostructures with a predetermined crystal orientation and large magnetocrystalline anisotropy will be developed. In particular, the kinetics of formation of the ordered tetragonal structure in films will be studied as a function of thickness, microstructure and internal stresses, and will be controlled and optimized by introducing compositional gradients in the films and by using suitable underlayers. Ternary Fe-Mn-Pt alloys will be developed to further enhance anisotropy and thus extend the range of achievable properties. The materials' magnetic response will be tailored for the targeted application via control of the microstructure and crystallographic orientation of the ordered structure. Nucleation and growth modes of the alloys within patterned structures of nanometer size or with high aspect ratios will be investigated in order to model prospective device components. Phase transformation and magnetic hardening in such confined structures will be analyzed as a function of geometry, structure size, growth conditions and underlayers in order to understand such processes and to develop feasible synthesis and post-processing conditions capable to achieve the properties of interest. NON-TECHNICAL SUMMARY:Permanent magnets are magnetic materials that once magnetized maintain a magnetic moment and become themselves useful sources of magnetic fields. They are ubiquitous in modern machinery and appliances, such as electrical motors, communication devices and information storage in computers and data banks. Advances in permanent magnet materials may allow for an extension of their functionalities to micro- and nanoscale devices, potentially leading to outstanding technological innovations; however, suitable materials and production methods are not yet available. This project seeks to integrate permanent magnet materials with available methods for microchip fabrication to ultimately enable the production of magnetic microscale devices. In order to do so, the formation and post-processing of Fe-Pt alloys will be investigated, with the aim to achieve materials exhibiting high performance even at extremely low size. Target applications will include novel information storage technologies and motion at the microscale for sensors and biomedical chips. Besides these technological aspects, this project will offer undergraduate research internships that will provide students with training and motivation to pursue graduate studies, as well as an opportunity of research management experience for graduate students. In turn, internships of graduate students within companies will enhance their scientific and professional development.