CAREER: Interplay of sliding ferroelectricity, spin and charge orderings in layered quantum materials

非技术摘要：该项目侧重于理解一类具有独特性质的新型量子材料的性质，称为二维层状材料。通过对新物理的建模、表征和工程化，本研究旨在了解材料的性质并实现对其的控制。这些材料可以为节能和高速存储和逻辑器件以及紧凑和可编程量子模拟器建立一个新的平台，以满足日益增长的信息和能源需求。与研究相结合，该项目旨在促进STEM的参与，重点关注来自STEM历史上代表性不足的群体和威斯康星州农村地区的本科生和K-12教师。PI与材料研究科学与工程中心（MRSEC）教育小组和威斯康星大学麦迪逊分校的工程博览会合作，组织“面向节能未来的二维铁电体”教育和推广计划，包括纳米材料研究、高中教室STEM教育活动开发和专业发展研讨会。技术摘要：二维（2D）层状材料具有磁性、强电子相关性、超导性和铁电性等重要的电子特性，是极具发展前景的量子材料平台。然而，由于目前大多数二维量子材料是非极性的，铁电性和其他量子性质的相互作用还未被探索。这种稀缺性阻碍了许多令人兴奋的研究课题，如二维多铁性、偶极哈伯德模型、可重构电荷顺序和超导二极管效应。最近从非极性层的极性堆叠中发现的“滑动铁电体”表明，绝大多数具有非极性化合物的二维材料都有可能设计出铁电体。铁电性可以通过层间滑动来切换，其中的超低范德华滑动势垒比任何其他铁电性都小得多。PI的方法是将各种非极性二维磁性单层设计和组装成极性堆叠结构，其中自旋和电荷顺序被假设为对铁电性驱动的堆叠演化敏感。为了充分理解新的量子有序和耦合物理，研究团队使用内部的多模态光、电和磁表征平台来同时访问不同空间、时间和能量尺度上的铁电性、磁性和电子相关性。此外，PI将通过静电掺杂和超快光工程对耦合强度进行量化和动态控制。该研究将促进对二维量子材料中多体相互作用的理解，并为在低功率电子、超高速自旋电子学和可重构量子模拟中使用已开发的极性和摩尔<s:1>二维磁体的设备应用铺平道路。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:This project focuses on understanding of properties of a new class of quantum materials with unique properties, known as two-dimensional layered materials. By modeling, characterizing, and engineering the novel physics, this research aims to understand the materials properties and achieve their control. These materials can establish a new platform for energy-efficient and high-speed memory and logic devices, and compact and programmable quantum simulators to address the growing information and energy demands. Integrated with the research, the project aims to promote participation in STEM, focusing on undergraduates and K-12 teachers from groups historically underrepresented in STEM and from rural areas in Wisconsin. The PI partners with the Materials Research Science and Engineering Centers (MRSEC) education group and Engineering EXPO at the University of Wisconsin-Madison to organize “2D ferroelectrics for energy-efficient future” education and outreach program including nanomaterials research, STEM education activities development for high school classrooms, and professional development seminars.Technical abstract:Two-dimensional (2D) layered materials are promising quantum material platforms with many important electronic properties, such as magnetism, strong electron correlation, superconductivity, and ferroelectricity. However, the interplay of ferroelectricity and other quantum properties is significantly unexplored because most current 2D quantum materials are nonpolar. Such scarcity hinders many exciting research subjects such as 2D multiferroics, dipolar Hubbard model, reconfigurable charge orderings, and superconducting diode effects. Recent discoveries of “sliding ferroelectricity” from polar stacking of nonpolar layers indicate it is possible to design ferroelectrics out of the vast majority of 2D materials with parent nonpolar compounds. The ferroelectricity can be switched via interlayer sliding, where the ultralow van der Waals sliding barrier is much smaller than that of any other ferroelectrics. The PI’s approach is to design and assemble various nonpolar 2D magnetic monolayers into polar stacking structures, where spin and charge orderings are hypothesized to be sensitive to ferroelectricity-driven stacking evolution. To fully understand the new quantum orderings and coupling physics, the research team use an in-house multimodal optical, electrical, and magnetic characterization platform to enable simultaneous access to ferroelectricity, magnetism, and electron correlation at various spatial, temporal, and energy scales. Furthermore, the PI will quantify and dynamic control of coupling strength by electrostatic doping and ultrafast light engineering. The research will advance the understanding of many-body interplay in two-dimensional quantum materials and pave the way for device applications using developed polar and Moiré 2D magnets in low-power electronics, ultrahigh-speed spintronics, and reconfigurable quantum simulation.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.