Collaborative Proposal: Harvesting electronic flat bands and strong spin-orbit coupling for novel functionalities in metal monochalcogenides

由单个原子层或几层组成的材料具有与大块材料截然不同的电子特性。例如，二维材料可以将高机械强度和光学透明度与有效的电荷传输联合收割机结合。这些属性可以用来创建具有新功能的新类别的设备。人们可以制造一种材料，它可以在开关的翻转下变得导电或绝缘，但也可以是磁性或非磁性的。这种材料可以开发超灵敏的光学或磁性传感器。本研究计画将针对其中一类可吸收材料-金属单硫族化合物，如硒化镓或硫化镓。研究人员将研究这些材料，并试图赋予它们特定的电，磁和光学特性后剥离，封装和扭曲。这项研究将与下一代物理学家，材料科学家和工程师的指导和培训相结合。两个团队成员都积极招募和指导来自代表性不足群体的本科生和研究生，同时也接触高中教师和学生。该团队与佛罗里达州立大学的国家高磁场实验室合作，为周围北佛罗里达县的学校开发实践教学材料。技术声明该合作项目的目标是利用III-VI族金属单硫族化物（MMC）家族固有的电子平带和强自旋轨道耦合（SOC），以实现栅极可调铁磁性和半金属性，分数量子霍尔（QH）态在大SOC的限制。这项工作将使新的自旋电子，谷电子和光电器件。研究者将：i）探索、调谐和理解大SOC区域中分数量子霍尔态的性质，这对拓扑量子计算具有影响; ii）由于半金属性及其与其他可能的相关态的相互作用，实现门可调谐铁磁性（如可能的超导性和相关相）在空穴掺杂少层金属基复合材料; iii）在基于过渡金属二硫属化物上的金属单硫属化物的异质结构中产生自旋极化电流和谷极化电流，以及iv）在具有莫尔超晶格的MMCs异质结构中实现栅极可调谐激子，用于具有前所未有的可调谐性水平的光电子学。该项目将直接支持每个参与机构的一名研究生。学生将在两个机构和其他国家设施之间流动。此外，两位主要研究人员将继续他们在指导本科生和高中生方面的既定努力，同时也招募和指导来自代表性不足群体的学生。该奖项反映了NSF的法定使命，并被认为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来支持。

NON-TECHNICAL DESCRIPTIONMaterials made from a single atomic layer or a few layers have electronic properties that profoundly differ from those of bulk materials. For example, two-dimensional materials can combine high mechanical strength and optical transparency with efficient charge transport. These properties could be exploited to create new classes of devices with novel functionalities. One could make a material that could become electrically conducting or insulating, but also magnetic or non-magnetic, at the flip of a switch. Such a material could enable development of ultra-sensitive optical or magnetic sensors. This research project will focus on one class of ultrathin materials—metal monochalcogenides such as gallium selenide or gallium sulfide. Researchers will investigate these materials and seek to endow them with specific electrical, magnetic, and optical properties upon exfoliation, encapsulation and twisting. This research will be integrated with the mentoring and training of the next generation of physicists, materials scientists, and engineers. Both team members actively recruit and mentor undergraduate and graduate students from underrepresented groups, while also reaching out to high school teachers and students. The team collaborates with the National High Magnetic Field Laboratory at Florida State University to develop hands-on instructional materials for schools in the surrounding North Florida counties.TECHNICAL DESCRIPTIONThe goal of this collaborative project is to harness the electronic flat bands and strong spin-orbit coupling (SOC) inherent to the family of the III-VI metal monochalcogenides (MMCs), to achieve gate-tunable ferromagnetism and half-metallicity, fractional quantum Hall (QH) states in the limit of large SOC. The work will enable novel spintronic, valleytronic and optoelectronic devices. Investigators will: i) explore, tune, and understand the nature of the fractional quantum Hall states in the regime of large SOC, which has implications for topological quantum computation; ii) achieve gate-tunable ferromagnetism due to half-metallicity and their interplay with other possible correlated states (such as possible superconductivity and correlated phases ) in hole-doped few-layer MMCs; iii) create spin- and valley-polarized currents in heterostructures based on metal monochalcogenides on transition metal dichalcogenides, and iv) achieve gate-tunable excitonics in MMCheterostructures with moiré superlattices, for optoelectronics with an unprecedented level of tunability. This project will directly support one graduate student at each participating institutions. The students will circulate among both institutions and other national facilities. In addition, both principal investigators will continue their established efforts at mentoring undergraduate and high school students, while also recruiting and mentoring students from underrepresented groups.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.