Beyond Binary: Understanding Multi-State Stability in Ferroelectrics

非技术描述：人们希望创造出在“超越二进制”意义上工作的设备--这意味着它们可以访问和利用多种状态(不仅仅是“0”？和当今标准计算机的“1”)来完成逻辑、存储器等功能。这样的系统可以模仿大脑的功能，并导致我们进行计算和存储数据的方式发生变革性的变化。这种方法对材料有严格的要求，而这些材料目前并不容易获得。这些材料包括可以根据材料的固有特性表现出多个、精确和唯一可寻址的“微态”的材料，这种材料不能随着时间的推移而显著波动或降解。寻找能够以这种方式发挥作用的合适材料仍然是一个首要的挑战。这个项目探索铁电材料，这种材料具有内在的稳定性和快速性，但传统上只表现出二元(而不是多态)函数，以寻找创建多态函数的新途径。该项目提供了对一系列应用非常重要的材料的新的基本了解，扩展了我们关于如何合成和控制对一系列下一代应用至关重要的复杂候选材料的知识，为新技术的开发提供了基础理解，包括对神经形态、超材料、逻辑/记忆和能量转换应用的潜在影响，并在尖端材料和实验方法方面培训和教育了现代劳动力，同时加深了我们合成/制造复杂材料的能力，从而实现了新的知识产权和创业努力。TECHNICAL细节：访问多种配置状态的能力(即，超越二进制)的材料将使我们的计算和存储数据的方式发生变革性的变化。神经形态计算结构(旨在模拟大脑中的神经元功能)需要基于可读的宏观顺序参数的材料，显示出多个、准确和唯一可寻址的“微状态”，该参数不会随着时间的推移而大幅波动或退化。需要新的可适应材料来实现这种变革性的技术。确定能够实现真正的神经形态(多态)原理的合适材料--结构、化学成分、形态和随机性--仍然是一个首要的挑战。该项目通过先进材料合成、制造和表征的创新组合，探索基础材料设计、控制和理解的各个方面，以实现本质双稳态铁电材料的新颖、多态功能。这项研究通过了解如何控制铁电材料中的极化、静电、梯度、弹性和其他能量，研究了从随机到确定性产生非挥发性多态的途径。这是通过以下方式实现的：1)使用外延生长来产生复杂的多基态结构，其中远程集体相互作用使多个态成为可能；2)开发设计应变和能量图景，从而在化学非均匀薄膜中实现非挥发性的多态稳定性；以及3)合成和应用电场和应力，以基于缺陷-极化耦合来诱导多态组态。这项研究为铁电的本质以及如何控制极化，如何以越来越高的精度制造复杂的多组分材料，如何在系统中发展铁电开关，以及如何在固态材料中实现多态功能提供了基础性的见解。该项目还为高技术研究人员提供培训和教育，为代表不足的学生群体提供研究机会，并可使重要技术在一系列重要技术领域发挥作用。

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.