CAREER: Design, control, and understanding of lateral textures in strongly correlated heterostructures

20世纪固体物理学最大的成就之一是对金属、半导体和绝缘体的量子力学描述。这种成功的硅等简单材料模型在实现了在纳米尺度上控制其性能以制造小型设备后推动了技术革命。然而，在减小它们的尺寸方面存在根本性的限制，这促使人们探索新材料以提供新的功能。因此，全世界的主要研究工作都在探索一类由更复杂的量子力学原理控制的新材料，称为“量子材料”，以推动技术革命。尽管如此，在小尺寸下控制它们的性能已被证明是具有挑战性的。该项目的目标是在纳米尺度上控制量子材料的电子行为。研究小组使用新发现的技术在原子水平上修改材料的化学性质和电子浓度，这将使我们能够控制电子特性，并具有精确的横向空间分辨率，达到纳米范围。有了这些知识，将开发具有深远影响的新设备概念。学生接受材料物理，设备概念和尖端实验技术的培训，并在支持少数民族学生的框架内进行分析。此外，为了扩大研究的影响，制作了一个播客，展示了固态物理研究的重要性和成功。技术摘要本项目源于在纳米尺度上获得对强关联过渡金属氧化物迷人的电子性质的控制的动机。这些“量子材料”是一个高度感兴趣的话题，因为它们的复杂和可调的量子相位。不久之后，人们意识到在薄膜和超晶格中外延生长它们可以提供调整特性的方法。然而，量子特性的横向控制被认为是困难的。该项目有两种方法来横向修改这些属性与空间分辨率在纳米到介观的长度尺度。首先，研究小组使用了一束聚焦到nm的He离子，它可以改变材料的氧化态，从而获得对基态性质的精确控制。其次，由于在光电半导体旁边分层量子材料可以产生前者对光刺激的显着敏感性，因此该团队对光电层的生长进行了图案化，以便在异质结构上创建光敏区域，其中量子相与顶部没有光电层的区域不同。参与研究的学生将获得现代材料科学的知识和同步加速器设施中最先进的x射线光谱工具。该项目还建立了一个框架，以支持少数民族背景的学生，并制作了一个音频播客，描述了上个世纪固体物理学的成功，突出了其现实世界的影响。该奖项反映了NSF的法定使命，并已被认为是值得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的支持。

Non-technical abstract Among the biggest triumphs of 20th-century solid-state physics was the quantum-mechanical description of metals, semiconductors, and insulators. This successful model for simple materials like Silicon propelled the technological revolution after achieving control of its properties at the nanometer scale to make small devices. However, there are fundamental limits on reducing their size, prompting the exploration of new materials to render novel functionalities. Thus, major research efforts worldwide explore a new class of materials governed by more complex quantum mechanical principles, known as “quantum materials”, to advance the technological revolution. Still, control of their properties at small sizes has proven to be challenging. This project has the goal of gaining control of the electronic behavior of quantum materials at the nanometer scale. The research team uses newly discovered techniques to modify a material’s chemistry and concentration of electrons at the atomic level, which will give us control of the electronic properties with exquisite lateral spatial resolution down to the nanometer range. With this knowledge, novel device concepts with far-reaching implications will be developed. Students are trained on materials physics, device concepts, and cutting-edge experimental techniques and analysis within a framework that supports minority students. Furthermore, to broaden the impact of the research a podcast is produced that showcases the importance and successes of research on solid state physics.Technical abstract This project stems from the motivation to gain control of the fascinating electronic properties of strongly correlated transition metal oxides at the nanometer scale. These “quantum materials” are a topic of high interest because of their complex and tunable quantum phases. Soon after, it was realized that growing them epitaxially in thin films and superlattices could provide ways of tuning the properties. However, lateral control of the quantum properties has been deemed difficult. This project has two ways to laterally modify these properties with a spatial resolution at nano- to mesoscopic length scales. First, the research team uses a beam of He ions focused down to nm, which can change a material’s oxidation state and thus gain exquisite control of the ground state properties. Secondly, since layering a quantum material next to an optoelectronic semiconductor can yield a dramatic sensitivity of the former to light stimulus, the team patterns the growth of the optoelectronic layer such as to create light-sensitive areas on the heterostructure, where the quantum phases are distinct from the areas without an optoelectronic layer on top. Students involved in the research acquire knowledge of modern materials science and state-of-the-art x-ray spectroscopic tools at synchrotron facilities. The project also builds a framework to support students of minority backgrounds and produces an audio podcast that describes the successes of last-century solid state physics highlighting its real-world implications.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.