Imaging correlations and charge order in transition metal dichalcogenide moiré systems

非技术摘要：材料的电子特性是由其内部原子和电子的排列决定的。在大多数情况下，这是由组成原子的化学性质决定的。然而，最近在分离原子薄晶体并将其堆叠在一起的能力方面取得的进展为设计新的合成材料提供了一条途径。这个项目研究了如何在相邻层之间增加一个小的扭曲来控制电子的位置和传播。特别是，旋转错位导致电子相互作用特别强烈，导致新的量子电子特性。这项研究使用纳米级传感器来成像所产生的电子位置，研究形成的新量子态，并确定它们可以控制的程度。预测的状态可能在低功耗电子产品、容错量子计算和高密度数据存储中得到应用。该项目还培训本科生和研究生从事量子技术的职业，通过暑期实习促进代表性不足的群体参与科学，并通过为高中生和当地科学节开发和实施外展活动来激励下一代研究人员。技术摘要：以较小的相对扭转角叠加晶格常数相近的范德华材料，可以产生特别平坦的电子带，易受强库仑相互作用的影响。该项目旨在研究由半导体过渡金属二硫族化合物（TMDs）组成的扭曲器件中可以实现的过多的多体相。本研究使用扫描单电子晶体管（SET）来测量局部电子可压缩性，并成像光电TMD系统中的电荷分布。主要目标包括：1)测量相关电子基态的能隙和激发；2)成像电荷有序相，如条纹和广义Wigner晶体及其熔化；3)探索这些涌现态对磁场、掺杂和扭转角的依赖关系，绘制出三角形Hubbard模型相图。moir<s:1> TMD系统为跨越广泛的哈伯德模型参数空间的量子模拟提供了前所未有的灵活性。作为电子性质的局部热力学探针，SET提供了对这种强相关材料平台的独特见解。此外，研究生和本科生获得范德华组装和低温扫描探针显微镜领域的经验。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。

Non-technical abstract: The electronic properties of materials are governed by the arrangement of atoms and electrons within them. In most cases, this is fixed by the chemistry of the constituent atoms. However, recent advances in the ability to isolate atomically thin crystals and stack them on top of each other provide a route to engineer new synthetic materials. This project investigates how adding a small twist between adjacent layers can be used to control the positions and propagation of electrons. In particular, the rotational misalignment causes the electrons to interact especially strongly with each other, leading to new quantum electronic properties. The research uses a nanoscale sensor to image the resulting electron positions, study the new quantum states that form, and determine the degree to which they can be controlled. The predicted states may have applications in low-power electronics, fault-tolerant quantum computing, and high-density data storage. The project also trains undergraduate and graduate students for careers in quantum technology, fosters the involvement of underrepresented groups in science through summer internships, and inspires the next generation of researchers by developing and implementing outreach activities for high school students and local science festivals.Technical Abstract: Stacking van der Waals materials with similar lattice constants at small relative twist angle can generate exceptionally flat electronic bands that are susceptible to strong Coulomb interactions. This project aims to investigate the plethora of many-body phases that can be realized in twisted devices composed from semiconducting transition metal dichalcogenides (TMDs). The research uses a scanning single-electron transistor (SET) to measure local electronic compressibility and to image charge distribution in moiré TMD systems. The primary goals include: 1) measuring the energy gaps and excitations of correlated electronic ground states; 2) imaging charge ordered phases, such as stripes and generalized Wigner crystals and their melting; and 3) probing the dependence of these emergent states on magnetic field, doping, and twist angle to map out the triangular Hubbard model phase diagram. Moiré TMD systems provide unprecedented flexibility for quantum simulation across a wide swath of Hubbard model parameter space. As a local thermodynamic probe of electronic properties, the SET provides unique insight into this strongly correlated materials platform. In addition, graduate and undergraduate students gain experience in the area of van der Waals assembly and low-temperature scanning probe microscopy.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.