Beyond Binary: Understanding Multi-State Stability in Ferroelectrics

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NON-TECHNICAL DESCRIPTION: There is desire to create devices that function in a "beyond binary" sense - meaning that they can access and make use of multiple states (not just the "0s"? and "1s" of standard computers today) to complete logic, memory, and other function. Such systems could emulate brain-like function and lead to transformative changes in how we do computation and store data. Such approaches have stringent requirements for materials which are not readily available today. These include materials that can exhibit multiple, precisely and uniquely addressable "microstates" based on an intrinsic feature of that material which must not fluctuate or degrade significantly over time. Identifying suitable materials that can function in this manner remains a foremost challenge. This project explores ferroelectric materials, which are intrinsic stable and fast, but have traditionally exhibited only binary (not multi-state) function to find new routes to create multi-state function. This project provides new fundamental understanding of materials that are important for a range of applications, expands our knowledge of how to synthesize and control complex, candidate materials critical for a range of next-generation applications, provides foundation understanding for novel technological development including potential impact on neuromorphic, metamaterial, logic/memory, and energy transduction applications, and trains and educates a modern workforce in cutting-edge materials and experimental approaches while deepening our abilities to synthesize/fabricate complex materials thereby enabling new intellectual property and entrepreneurial endeavors.TECHNICAL DETAILS: The ability to access multiple configuration states (i.e., going beyond binary) in materials will enable transformative changes in how we do computation and store data. Neuromorphic computing architectures (designed to emulate neuron function in the brain) require materials exhibiting multiple, precisely and uniquely addressable "microstates" based on a readable macroscopic order parameter which does not fluctuate or degrade significantly over time. New adaptable materials are required to enable such transformative technologies. Identifying suitable materials - structures, chemistries, morphologies and stochasticities - that enable true neuromorphic (multi-state) principles remains a foremost challenge. This program explores aspects of fundamental materials design, control, and understanding through an innovative combination of advanced materials synthesis, fabrication, and characterization to enable novel, multi-state function in intrinsically bi-stable ferroelectric materials. The research investigates routes to transition from stochastic to deterministic production of non-volatile multi-states by understanding how to control the polarization, electrostatic, gradient, elastic, and other energies in ferroelectrics. This is achieved by 1) using epitaxial growth to produce complex, multi-ground state domain architectures wherein long-range collective interactions enable multiple states; 2) developing designer strain and energy landscapes that enable non-volatile, multi-state stability in chemically-inhomogeneous films; and 3) synthesis and application of electric field and stress to induce multi-state configurations based on defect-polarization coupling. The research provides foundational insights about the nature of ferroelectricity and how polarization can be controlled, how to produce complex, multi-component materials with ever-increasing precision, how ferroelectric switching evolves in systems, and how multi-state function can be achieved in solid-state materials. This project additional provides for training and education of high-tech researchers, research opportunities for underrepresented student groups, and could enable technologies of importance to a range of important technical fields.