Phase-Field Model of Inhomogeneous Ferroelectric Crystals Under Ultrafast Stimuli

该奖项支持旨在更好地理解铁电材料的理论研究、计算建模和教育。铁电体包括一类晶体材料，在许多类型的设备中都有重要的技术应用，如医疗和水下换能器、传感器、非易失性存储器、节能冷却。这项研究计划的目标是发展必要的材料理论和计算机代码，以了解这些铁电晶体在受到外部超快刺激时的反应，例如温度突然升高或表面上的电场脉冲。研究人员还将探索这种外部刺激可能产生的新物质状态。该小组将利用一个实验合作者网络，根据实验验证已开发的理论和计算机代码。发展的理论和计算机代码可以用于描述其他材料系统中的类似现象，例如用于存储应用的铁磁材料中的超快磁化动力学，以及电子开关器件中新电子相之间的潜在形成和转变。预计该项目不仅会通过推进材料理论对材料科学产生影响，还会对应用数学和材料力学产生影响。PI还将把若干教育和外联活动纳入研究；其中包括：1)开发材料建模软件的开源版本，并组织相关的年度研讨会；2)招募本科生使用软件包进行研究；3)通过参与全校范围的组织外展活动，并通过招募女性和代表性不足的少数族裔在PI的实验室进行研究，让她们参与STEM。该奖项支持旨在更好地理解铁电材料的理论研究、计算建模和教育。铁电体包括一类晶体材料，在许多类型的设备中都有重要的技术应用，如医疗和水下换能器、传感器、非易失性存储器、节能冷却。本研究计划的目标是了解非均匀铁电晶体在外部超快刺激和晶体内部复杂静电和弹性相互作用下的动态响应。PI和他的团队将开发一种动态相场方法来建模，预测和理解超快刺激下极化和应变域模式的动态时空演变，考虑到远程静电和弹性相互作用以及畴壁能量。该小组还将探索当非均匀晶体从外部刺激的激发态松弛回原始或新的平衡态时可能出现的新的瞬态或亚稳态域态；这些可能是在热力学条件下通常无法观察到的隐藏状态。研究人员将研究非均匀晶体在超快外部刺激下的铁电和压电响应，并将探索超快频率下的热、电、机械和多功能响应。该小组将利用一个实验合作者网络，根据实验验证已开发的理论和计算机代码。所提出的动态相场方法可以推广到许多其他问题的研究中。例如，它可以用于求解微磁相场方程与弹性动力学方程的耦合，以探索具有强磁弹性耦合的铁磁材料的超快磁化动力学。所提出的方法也可以扩展到研究电子-晶格耦合现象和新电子相的潜在形成，通过在超快刺激下引入电子自由度，允许操纵电子相变，如相关系统中的金属-绝缘体相变。预计该项目不仅会通过推进材料理论对材料科学产生影响，还会对应用数学和材料力学产生影响。PI还将把若干教育和外联活动纳入研究；其中包括：1)开发铁材料建模软件的开源版本，并组织相关的年度研讨会；2)招募本科生使用软件包进行研究；3)通过参与全校范围的组织外展活动，并招募女性和代表性不足的少数族裔在PI的实验室进行研究，让她们参与STEM。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NONTECHNICAL SUMMARYThis award supports theoretical research, computational modeling, and education that aim towards better understanding ferroelectric materials. Ferroelectrics comprise a class of crystalline materials that have found important technological applications in many types of devices, such as medical and underwater transducers, sensors, non-volatile memories, energy-efficient cooling. The goal of this research program is to develop the necessary materials theories and computer codes to understand how these ferroelectric crystals respond when subjected to external ultrafast stimuli, such as a sudden temperature rise or an electric-field pulse on their surface. The researchers will also explore possible new material states that may emerge as a result of such external stimulation. The group will utilize a network of experimental collaborators to validate the developed theory and computer codes against experiments. The developed theory and computer codes could find use in describing similar phenomena in other materials systems, for example the ultrafast magnetization dynamics in ferromagnetic materials for memory applications, and the potential formation of and transitions between novel electronic phases in electronic switching devices.The project is expected to have impact not only on materials science by advancing materials theories, but also on applied mathematics and the mechanics of materials. The PI will also integrate several educational and outreach activities into the research; these include: 1) the development of an open-source version of modeling software for materials and the organization of an associated annual workshop, 2) the recruitment of undergraduate students to perform research using the software package, and 3) the engagement of women and underrepresented minorities in STEM via participation in university-wide organized outreach activities and by recruiting them to perform research in the PI's laboratory.TECHNICAL SUMMARYThis award supports theoretical research, computational modeling, and education that aim towards better understanding ferroelectric materials. Ferroelectrics comprise a class of crystalline materials that have found important technological applications in many types of devices, such as medical and underwater transducers, sensors, non-volatile memories, energy-efficient cooling. The goal of this research program is to understand the dynamic responses of inhomogeneous ferroelectric crystals under external ultrafast stimuli and in the presence of complex electrostatic and elastic interactions among domains within the crystal. The PI and his group will develop a dynamical phase-field method to model, predict, and understand the dynamical spatiotemporal evolution of polarization and strain domain patterns under ultrafast stimuli, taking into account long-range electrostatic and elastic interactions and domain-wall energy. The group will also explore novel transient or metastable domain states that may emerge when an inhomogeneous crystal relaxes from its externally stimulated excited state back to the original or a new equilibrium state; these could be hidden states that are normally not observable under thermodynamic conditions. The researchers will investigate ferroelectric and piezoelectric responses of inhomogeneous crystals under ultrafast external stimuli, and will explore thermal, electric, mechanical, and multifunctional responses at ultrafast frequencies. The group will utilize a network of experimental collaborators to validate the developed theory and computer codes against experiments.The proposed dynamic phase-field method can be extended to the study of many other problems. For example, it can be adapted to solve a micromagnetic phase-field equation coupled with an elastodynamic equation for exploring ultrafast magnetization dynamics in ferromagnetic materials with strong magnetoelastic coupling. The proposed approach can also be extended to the study of electron-lattice coupling phenomena and the potential formation of novel electronic phases by introducing electronic degrees of freedom under ultrafast stimuli, allowing the manipulation of electronic phase transitions such as metal-insulator transitions in correlated systems.The project is expected to have impact not only on materials science by advancing materials theories, but also on applied mathematics and the mechanics of materials. The PI will also integrate several educational and outreach activities into the research; these include: 1) the development of an open-source version of modeling software for ferroic materials and the organization of an associated annual workshop, 2) the recruitment of undergraduate students to perform research using the software package, and 3) the engagement of women and underrepresented minorities in STEM via participation in university-wide organized outreach activities and by recruiting them to perform research in the PI's laboratory.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.