氢化钙钛矿镍酸盐突触器件的红外纳米成像
Infrared Nanoimaging of Hydrogenated Perovskite Nickelate Synaptic Devices
AI总结：
本研究利用operando红外纳米成像揭示了氢化镍酸钕突触器件中外加电场对掺杂剂纳米尺度分布的扰动机制，发现条纹相决定宏观电学特性，并结合理论与原位实验阐明了晶格膨胀对扩散的阻碍作用。
摘要：
由钙钛矿镍酸盐等关联氧化物制成的固态器件，通过模拟生物突触功能，在神经形态计算方面极具前景。然而，在纳米尺度上理解掺杂剂行为，对阐明其基本机制构成了巨大挑战。在此，我们对氢掺杂关联钙钛矿——氢化镍酸钕（H-NdNiO3）器件进行了operando红外纳米成像，揭示了外加电场如何在纳米尺度上扰动掺杂剂分布。这种扰动导致了垂直于外加电场的不同电导率的条纹相，从而决定了器件的宏观电学特性。结合密度泛函理论计算，高光谱nano-FTIR成像揭示了H-NNO与OH伸缩振动模式相关的多振动态实空间图，及其对掺杂剂浓度的依赖性。此外，多余电荷的局域化在NNO中诱发了面外晶格膨胀，这已通过原位X射线衍射证实，并产生了一种阻碍进一步扩散的应变。我们的结果和所提出的技术，对忆阻器和神经形态器件这一快速发展的领域具有巨大潜力，在这些领域中，纳米尺度的离子运动是功能的基础。
英文摘要：
Solid-state devices made from correlated oxides such as perovskite nickelates are promising for neuromorphic computing by mimicking biological synaptic function. However, comprehending dopant action at the nanoscale poses a formidable challenge to understanding the elementary mechanisms involved. Here, we perform operando infrared nanoimaging of hydrogen-doped correlated perovskite, neodymium nickel oxide (H-NdNiO3) devices and reveal how an applied field perturbs dopant distribution at the nanoscale. This perturbation leads to stripe phases of varying conductivity perpendicular to the applied field, which define the macroscale electrical characteristics of the devices. Hyperspectral nano-FTIR imaging in conjunction with density functional theory calculations unveil a real-space map of multiple vibrational states of H-NNO associated with OH stretching modes and their dependence on the dopant concentration. Moreover, the localization of excess charges induces an out-of-plane lattice expansion in NNO which was confirmed by in-situ - x-ray diffraction and creates a strain that acts as a barrier against further diffusion. Our results and the techniques presented here hold great potential to the rapidly growing field of memristors and neuromorphic devices wherein nanoscale ion motion is fundamentally responsible for function.
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