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

非技术描述由单个原子层或几个原子层制成的材料具有与大块材料截然不同的电子性质。例如，二维材料可以将高机械强度和光学透明度与高效的电荷传输结合在一起。这些特性可以被利用来创造具有新功能的新设备类别。人们可以通过拨动开关来制造一种材料，这种材料可以成为导电或绝缘的，也可以是磁性的或非磁性的。这种材料可以开发出超灵敏的光学或磁性传感器。这项研究项目将集中在一类超薄材料-金属单醇化合物，如硒化镓或硫化镓。研究人员将对这些材料进行研究，并寻求在剥离、封装和扭曲时赋予它们特殊的电、磁和光学性能。这项研究将与指导和培训下一代物理学家、材料科学家和工程师相结合。这两个团队成员都积极地从代表性不足的群体中招募和指导本科生和研究生，同时也接触到高中教师和学生。该团队与佛罗里达州立大学的国家高磁场实验室合作，为周围北佛罗里达州的学校开发动手教学材料。技术描述这个合作项目的目标是利用III-VI金属单醇化合物(MMC)家族固有的电子平带和强烈的自旋轨道耦合(SOC)，在大型SOC的限制下实现栅极可调的铁磁性和半金属、分数量子霍尔(QH)态。这项工作将使新型自旋电子、电子电子和光电子设备成为可能。研究人员将：i)探索、调谐并了解大尺寸SOC区域中分数量子霍尔态的性质，这对拓扑量子计算具有重要意义；ii)由于半金属性质及其与其他可能的相关态(如可能的超导电性和相关相)的相互作用，实现栅可调谐的铁磁性；iii)在基于过渡金属二卤化物上的金属单硫化物的异质结中产生自旋极化和谷极化电流，以及iv)在具有前所未有的可调谐水平的光电子学中，利用Moiré超晶格在MMC异质结中实现栅调谐激子。该项目将直接资助每个参与院校的一名研究生。学生们将在这两个机构和其他国家设施之间流动。此外，两位首席调查人员将继续他们既定的努力，指导本科生和高中生，同时也招募和指导代表不足的群体的学生。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.