Transport studies of periodically driven electronic systems

非技术描述：个人电脑、万维网、手机、高清晰度电视、电子传感器，以及预期的自动驾驶汽车和人工智能，有助于推动美国国内生产总值的增长，这些增长引擎严重依赖半导体电子材料方面的技术进步。尽管相关的电子材料通常在三维中处于自然平衡稳定状态，但理论研究表明，当这些材料中的组成电子被人为重新排列时，可能实现新的能力，例如仅将它们限制在二维。这项研究考察了受到低能量光源激发的二维系统的电子性质，以寻找预测的物理现象，以期实现潜在的应用。这项研究是及时的，因为原子分层材料的最新进展极大地扩大了可用于此类研究的材料的范围和可观察到的新现象的范围。这项研究项目是在佐治亚州立大学进行的，佐治亚州立大学是服务于全国最多样化人口的大学之一。它将涉及本科生和高中生，包括那些来自历史上代表性不足的群体和女性的学生，并将他们的能力转化为在STEM领域追求职业道路，为他们提供早期接触支持性、建立信心和研究经验的机会。该项目还将有助于为电子、光电子、国防和无线通信行业增加国家科技技能基地中代表不足的社会群体。技术描述：本研究实验检测了半导体异质结构和二维原子层材料在低能稳态光激发下的磁电响应，包括单层、双层和扭曲的双层石墨烯、原子薄的六方氮化硼(h-BN)，以及可能的过渡金属-二卤化物。在上述材料体系中，稳态低能光激发下的光激发输运大多未被探索，部分原因是在高磁场、低温、低能光激发下同时获得高质量样品所遇到的实验困难。由研究生、本科生和高中生组成的研究小组将利用电子束光刻、等离子体刻蚀和金属化技术构建层状半导体器件和2D原子层状晶体，并在微波、毫米波和太赫兹光激励下测试磁场存在下的电接触和非接触器件的性能。在这里，一些令人感兴趣的具体问题包括：在抛物型GaAs/AlGaAs和双层石墨烯系统中，以及在线性分散的单层石墨烯系统中，研究电子和复合费米子的辐射感生磁阻振荡和相关的零电阻态的粒子特性。另一个目的是阐明单层石墨烯中电子和复合费米子辐射诱导振荡的基场与费米波矢的关系。在扭曲的双层石墨烯体系中，一个目的是研究速度重整化随扭曲角的变化。在STEM的其他方面，将向当地高中科学教师伸出援手，通过在线讲座/研讨会让学生接触纳米科学，并在佐治亚州立大学招待这些高中生进行基于纳米科学的实验室调查。该奖项反映了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 Description: The personal computer, the world wide web, the cell phone, high-definition television, electronic sensors, and the expected autonomous car and artificial intelligence, help drive the growth of the United States gross domestic product and these growth engines rely heavily upon technological advances made in semiconductor electronic materials. Although associated electronic materials are typically utilized in their natural equilibrium steady states in three dimensions, theoretical studies suggest the possibility of realizing new capability when the constituent electrons in these materials are artificially rearranged, such as confining them only to two-dimensions. This research examines the electronic properties of two-dimensional systems subjected to excitation from low energy light sources in search of predicted physical phenomena, with a view towards potential applications. This research is timely because recent advances in atomically layered materials has greatly expanded both the universe of available materials for such studies and scope of observable new phenomena. This research project is carried out at Georgia State University, one of the universities which serves the most diverse population in the nation. It will involve undergraduate and high school students, including those from historically underrepresented groups and women, and translate their abilities into the pursuit of career paths in the STEM field, by providing them early exposure to a supportive, confidence building, research experience. The project will also help to add underrepresented sections of society to the nation’s science and technology skill base for the electronics, photonics, defense, and wireless communications industries. Technical Description: This research experimentally examines the magnetoelectronic response under low energy steady state photoexcitation of semiconductor heterostructures and 2D atomic-layered materials including mono-layer, bilayer, and twisted bilayer graphene, atomically thin hexagonal boron nitride (h-BN), and possibly transition metal-dichalcogenides. Photo-excited transport under steady state low energy photoexcitation is mostly unexplored in the above-mentioned material systems partly because of the experimental difficulties encountered in simultaneously bringing together high magnetic fields, low temperatures, low energy photoexcitation over a wide band, with good quality samples. The research team consisting of graduate students, undergraduates, and high school students, will build up layered semiconductor devices and 2D atomic-layered crystals by applying electron beam lithography, plasma etch, and metallization; and examine the properties of electrically contacted and non-contacted devices in the presence of a magnetic field under microwave, mm-wave, and terahertz photoexcitation. Here, some specific problems of interest include the study, to measure particle characteristics, of radiation-induced magnetoresistance oscillations and associated zero-resistance states, for electrons and composite fermions, in the parabolic GaAs/AlGaAs and bilayer graphene systems, as well as in the linearly dispersed monolayer graphene system. Another aim is to clarify the dependence of the fundamental field for the radiation induced oscillations for both electrons and composite fermions on the Fermi wave vector in monolayer graphene. In the twisted bilayer graphene system, one aim is to study the velocity renormalization versus the twist angle. In other STEM aspects, there will be outreach to local high school science teachers to expose the students to nanoscience via online lectures/seminars and host such high school students for nanoscience-based laboratory investigations at Georgia State University.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.