EAGER: Chemical Order/Disorder Enabled Phononic Memory in PbSc0.5Ta0.5O3

该项目研究了一种新的方法来存储对电磁脉冲不敏感的计算信息。在这种方法中，热量通过可以处于两种不同状态的材料进行传导。在一种状态下，材料将具有以特定顺序排列的相似原子，而在另一种状态下，原子将占据随机位置。激光脉冲用于局部加热材料并将其从一种状态转变为另一种状态，然后作为开态或关态存储器。计算预测，不同原子的固溶体将根据化学顺序不同地传导热量，但尚未得到实验证明。这种强化的计算方法增强了信息安全性和计算弹性，以抵御不可避免的电磁脉冲，例如太阳耀斑产生的电磁脉冲。该项目还旨在教育公众了解浪费为热量的能量的大小以及如何利用和转换为有用的能量。该研究项目研究化学有序对声子携带热量的材料系统中热导率的作用，并将推进对如何操纵局部化学有序以实现所需声子或热响应的基本理解。所研究的材料是钽钪酸铅，一种钙钛矿氧化物，可以根据热历史在八面体配位阳离子位点上化学有序或无序。该项目采用外延生长，通过脉冲激光烧蚀单晶钛酸锶衬底上的外延钌酸锶导电氧化物电极。使用时域热反射评估的热导率建立了具有不同化学顺序的钽酸钪铅的热导率。高能激光脉冲局部加热钽钪酸铅材料，导致化学顺序和热导率的空间控制。钙钛矿钽酸钪铅与钛酸锆铅是同构的，钛酸锆铅先前已被证明可用作声子调节材料。该项目开发了必要的钙钛矿热存储器，以配合热调节器，这是开发声子计算机的重要一步。此外，这项研究测试了计算预测，即化学有序材料在低温下比无序材料具有更高的热导率，但在高温下会表现出热导率的交叉，这尚未得到实验验证。通过声子计算和存储信息的能力是实现电磁脉冲弹性计算的潜在途径，这对信息安全至关重要。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project investigates a new means to store computed information that is not sensitive to electromagnetic pulses. In this method heat is conducted through a material that can be in two different states. In one state, the material will have like atoms arranged in a specific order, while in the other state the atoms will inhabit random positions. Laser pulses are used to locally heat the material and transform it from one state to the other, which then serve as either on-state or off-state memories. It has been computationally predicted that solid solutions of various atoms will conduct heat differently depending on the chemical order, but has not been experimentally proven. This hardened computing method enhances information security and computing resiliency against unavoidable electromagnetic pulses, such as those resulting from solar flares. This project also seeks to educate the public on the magnitude of energy wasted as heat and how it can be harnessed and converted for useful energy.This research project studies the role of chemical order on thermal conductivity in a material system where heat is carried by phonons, and will advanced the fundamental understanding of how local chemical order can be manipulated to achieve a desired phononic or thermal response. The material studied is lead scandium tantalate, a perovskite oxide that can be chemically ordered or disordered on the octahedrally coordinated cation site depending on the thermal history. The project employs epitaxial growth via pulsed laser ablation on single crystal strontium titanate substrates with an epitaxial strontium ruthanate conductive oxide electrode. Thermal conductivity evaluated using time domain thermoreflectance establishes the thermal conductivity of the lead scandium tantalate with varying degrees of chemical order. High energy optical laser pulses heat the lead scandium tantalate material locally resulting in spatial control of chemical order and thermal conductivity. The perovskite lead scandium tantalate is isostructural with lead zirconium titanate, which has been previously shown to serve as a phonon regulating material. This project develops the necessary perovskite thermal memory to accompany the thermal regulator, which is an important step toward developing a phonon computer. Furthermore, this research tests computational predictions that posit a chemically ordered material possesses a higher thermal conductivity at low temperatures than a disordered counterpart, but that will exhibit a cross-over in thermal conductivity at elevated temperatures, which is not yet experimentally validated. The ability to compute and store information via phonons is a potential path toward electro-magnetic pulse resilient computing, which is vital for information security.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.