Multiscale theory of memristive materials systems

技术总结该奖项支持记忆材料的计算和理论研究以及教育。由于电子和离子导电之间的耦合，记忆材料表现出内在的非线性导电行为，后者是由空位和间隙等缺陷所介导的。通常称为阻性开关材料的子类材料可以在高阻状态和低阻状态之间切换，并且可能是构建阻性随机存取存储器的理想材料。更广泛地说，记忆材料在其I-V特性中具有滞后环。除了存储应用，它们还可以导致新的模拟应用，甚至生物启发的神经形态电路，这两种电路都利用I-V特性中的逐渐“开关”。然而，缺乏对缺陷动力学及其与电子传导相互作用的准确描述，已成为实现材料潜力的主要障碍。PI将专注于揭示记忆现象中的物理和化学基础。PI将建立一个基于使用现实原子模型的第一原理量子力学计算的多尺度理论框架，并将其应用于研究各种材料系统中的记忆开关。原子尺度的研究将包括缺陷、它们的相互作用和相关的电子能级的第一性原理计算。缺陷对导电性的影响将用第一原理输运程序来探测。在动力学蒙特卡罗模型中引入缺陷能量学，以获得材料真实的I-V行为。由于重点放在记忆开关的微观机制上，因此该研究将确定影响其开关性能的材料的基本性质。这项拟议的研究还将构建基于物理的状态方程，这些方程将成为器件和电路设计的基础。将继续与大学和工业界的实验和工程小组进行互动。将向高中和更广泛的社会进行广泛的教育推广。非技术性总结该奖项支持计算和理论研究以及记忆材料方面的教育。记忆材料以一种有趣的方式导电，可以制造出用于记忆的设备，成为新型模拟电路的基础，甚至可以引入模仿生物大脑功能的神经形态计算机。在许多材料中，流过材料的电流与材料上的电压成线性关系。在记忆材料中，电流和电压之间的关系是非线性的。虽然电子在金属中的传导只源于电子的流动，但记忆材料中的非线性起源于材料中电子和离子的耦合传导，后者是由材料中原子规则排列的缺陷所调节的，例如缺失的原子或空位。PI旨在对电流通过电子和离子耦合运动通过这些材料的方式以及记忆行为背后的机制有一个基本的了解。PI的目的是进行理论和计算研究，以便在微观水平上阐明导电过程，确定记忆行为的起源，并建立材料的原子尺度性质与其对导电现象的影响之间的关联。与实验者和工程师的广泛互动将是该计划的一部分。广泛的教育推广将使高中和社区能够获得进步。

TECHNICAL SUMMARYThis award supports computational and theoretical research and education on memristive materials. Memristive materials exhibit intrinsic nonlinear conduction behavior due to the coupling between electronic and ionic conduction, the latter being mediated by defects, such as vacancies and interstitials. A subclass of materials, usually referred to as resistive-switching materials, can be switched between a high-resistance state and a low-resistance state and may be ideal for constructing resistive random access memory. More generally, memristive materials feature a hysteresis loop in their I-V characteristics. Besides memory applications, they can lead to new analog applications and even bio-inspired neuromorphic circuits, both of which utilize a gradual 'switch' in the I-V characteristics. However, the lack of an accurate description of defect dynamics and its interplay with electronic conduction has become a major obstacle for realizing the potential of the materials. The PI will focus on revealing the underlying physics and chemistry in memristive phenomena.The PI will establish a multiscale theoretical framework based on first-principles quantum-mechanical calculations using realistic atomic models and apply it to investigate the memristive switching in various materials systems. The atomic-scale investigation will include first-principles calculations of defects, their interactions, and pertinent electron energy levels. The effects of the defects on the conductivity will be probed using first-principles transport codes. Defect energetics will be incorporated in a kinetic Monte-Carlo model to obtain realistic I-V behavior of the materials. Since the focus is on the microscopic mechanisms of the memristive switching, the proposed research will identify the fundamental properties of the materials that affect their switching performance. The proposed research will also construct physics-based state equations that will be the foundation of device and circuit design. Interactions with experimental and engineering groups at universities and industry will be pursued. Extensive education outreach will be made to high schools and the broader society.NON-TECHNICAL SUMMARYThis award supports computational and theoretical research and education on memristive materials. Memristive materials conduct electricity in an interesting way that can lead to devices for memory applications, be a basis for new types of analog circuits, and even introduce neuromorphic computers that mimic the biological brain functions. In many materials, electric current flowing through the material is linearly related to the voltage across the material. In memristive materials, the relation between current and voltage is nonlinear. While conduction of electrons through metals originates from the flow of electrons alone, the non-linearity in memristive materials originates from the coupled conduction by electrons and conduction by ions in the materials, the latter being mediated by defects in the regular arrangement of atoms in the materials, such as missing atoms or vacancies. The PI aims to develop a fundamental understanding of the way electric current flows through these materials by coupled electron and ion motion and the mechanisms that underlie the memristive behavior. The PI aims to conduct theoretical and computational investigations in order to illuminate the conduction process at the microscopic level, identify the origin of the memristive behavior, and establish correlations between atomic-scale properties of materials and their implications for conductive phenomena. Broad interactions with experimentalists and engineers will be a part of the program. Extensive education outreach will make advances accessible to high schools and the community.