Topological Electromagnetic Sensors

摘要：传感器技术的不断发展需要创新的方法来降低功耗，提高灵敏度，分辨率和工作温度。最近在拓扑绝缘体中发现的轴子电磁耦合对传感器技术的性能有很大的改善前景。这种新型材料具有体绝缘能隙和受时间反转对称性保护的无间隙狄拉克-锥表面态。与传统半导体不同，由于表面上独特的自旋输运，因此禁止反向散射，从而导致令人兴奋的非耗散应用。引人注目的电磁耦合和半整数量子霍尔效应在纳米电子学和自旋电子学中开辟了全新的革命性应用。本项目拟利用拓扑绝缘体中的轴子电磁耦合效应，构建超越传统磁强计性能的超灵敏磁传感器。知识价值：本项目的知识价值包括(i)展示了拓扑绝缘体中尚未被实验探索的有趣的电磁耦合效应；（ii）提高了对材料性质的理解，包括表面的磁性掺杂，以及涉及磁性氧化物的异质结构的生长，其中表面间隙被打开以调用耦合效应；（iii）探索一种在高温下检测表面态的新型量子电容方法；（iv）在环境温度下工作的拓扑传感器的发明具有前所未有的灵敏度和空间分辨率。变革的概念包括将低耗散拓扑保护的拓扑绝缘体表面态用于电子和自旋电子器件，如磁换能器、电可调谐电感器和量子计算系统。更广泛的影响：拟议的项目将导致一种新的磁力计技术，利用拓扑绝缘体的体积特性和表面状态。高灵敏度、高空间分辨率和低耗散性能可以满足传感器技术的要求。这个成功的项目有望在医学研究中有潜在的应用，如脑电波探测和在低磁场下增强磁灵敏度的军事监视。该项目的发展可以潜在地提高EPSCoR州#8722（爱荷华州）在磁传感器设备领域的竞争力。除了技术影响外，该计划还具有强大而全面的教育成分。学生将在电气工程、物理和材料科学这一高度跨学科的领域获得宝贵的研究经验，从而提高他们在整个职业生涯中追求创新的训练和能力。PI将通过爱荷华州立大学现有的“科学之旅”和“女性科学与工程项目”，从代表性不足的群体中招收学生，特别是女学生，从而创造一个多元文化的环境。将为他们的教育提供全额学费、研究援助和资源。学生可以有充分的机会学习最新的传感器技术，并获得拓扑绝缘体的实践经验。这样的经历将开阔他们的科学视野，从而成为他们未来职业生涯的宝贵财富。该计划的成果将被纳入传感器技术课程，并通过同行评审的出版物在会议上传播。PI还将积极参与爱荷华州立大学的K-12课程，并继续提供纳米技术和磁学方面的小型讲座。拓扑电磁传感器的研究前沿可以作为有趣的演示，旨在激发学生的好奇心、创造力和对科学技术的热情。

Abstract:The continuing evolution of sensor technology requires innovative approaches for reducing power consumption and improving sensitivity, resolution & operating temperature. The recent discovery of axion electromagnetic coupling in topological insulators holds great promise for drastic improvement of performance in sensor technology. This new class of materials has a bulk insulating energy gap and gapless Dirac-cone surface states which are protected by time-reversal symmetry. Unlike in traditional semiconductors, back-scattering is prohibited because of unique spin transport on the surfaces, leading to exciting non-dissipative applications. The striking electromagnetic coupling and half-integer quantum Hall effects open up completely new and revolutionary applications in nanoelectronics and spintronics. This project proposes to exploit the axion electromagnetic coupling effect in topological insulators and to build ultra-sensitive magnetic sensors that surpass the performance of traditional magnetometers.Intellectual Merit: The intellectual merit of this project includes (i) the demonstration of the intriguing electromagnetic coupling effect in topological insulators that has not yet been experimentally explored; (ii) the improved understanding of material properties including magnetic doping of surfaces, and the growth of heterostructures involving magnetic oxides in which the surface gap is opened to invoke the coupling effect; (iii) the exploration of a novel quantum capacitance approach for the detection of surface states at high temperatures; and (iv) the invention of topological sensors operating at ambient temperature with unprecedented sensitivity and spatial resolution. The transformative concepts include the use of low-dissipation topologically protected surface-states of topological insulators for electronic and spintronic devices such as magnetic transducers, electrically tunable inductors, and quantum computation systems.Broader Impacts: The proposed project will lead to a new magnetometer technology that exploits bulk properties and surface states of topological insulators. The high sensitivity, high spatial resolution and low-dissipation performance can satisfy the demanding requirements in sensor technology. The successful project is expected to have potential applications in medical research such as brain wave detection and in military surveillance with an enhanced magnetic sensitivity at low fields. The development of this project can potentially improve the competitiveness of the EPSCoR state #8722 (Iowa State) in the area of magnetic sensor devices. Besides the technological impacts, the program has a strong and comprehensive education component. Students will gain invaluable research experience in this highly interdisciplinary area of electrical engineering, physics, and materials science, leading to enhanced training and ability to pursue innovations for the entirety of their careers. The PI will create a multicultural environment by recruiting students from underrepresented groups, particularly female students, through the existing outreach programs "Science Bound" and "Program for Women in Science and Engineering" at Iowa State University. Full tuitions, research assistances and resources will be supplied for their education. The students can have ample opportunities to learn state-of-the-art sensor technology and gain hand-on experience on topological insulators. Such experience will broaden their scientific horizons and thus become invaluable assets to their future careers. The outcomes of the program will be incorporated into a course on sensor technology and disseminated in conferences & through peer-reviewed publications. The PI will also actively participate in the K-12 program at Iowa State and continue to offer mini-lectures on nanotechnology and magnetism. Research frontiers of the topological electromagnetic sensors can be included as interesting demonstrations, aiming to stimulating students' curiosity, creativity, and enthusiasm in science and technology.