MRI: Development of an Ultra-high Sensitivity Scanning SQUID Multi-Function Microscope for Nanoscale Magnetometry, Susceptometry, and Thermometry

技术进步越来越依赖于新材料的开发，通常需要深入了解它们在纳米级的物理特性。传统的测量方法只测量整体或非局部量是不够的。新一代的仪器必须开发，可以探测材料的性质在纳米尺度。然而，在这些尺度下，信号的强度（例如，电、磁或热）的影响很弱，因此这些仪器也必须非常灵敏。该项目支持开发基于非侵入性超导量子干涉器件（SQUID）传感器的低温扫描探针显微镜，该传感器对磁和热特性具有超高灵敏度。该仪器中采用的特定nanoSQUID技术，即纳米移液管尖端的SQUID，可应用于广泛的系统。该仪器使材料研究在超导性，纳米磁性，自旋电子学，量子信息和计算，拓扑材料，量子热传输和耗散机制。多功能扫描探针显微镜是通过跨学科的合作开发的教师，工作人员和学生在丹佛和博尔德校区的科罗拉多大学。它的发展培养了一名全日制研究生和三名本科生，他们在仪器仪表，低温学以及其他多个物理和工程主题方面受到两名高级教师和两名高级工程人员的指导，他们具有互补的专业领域。这台仪器是科罗拉多前线范围内一套纳米光谱工具的一部分，它带来了学者，国家实验室科学家，和来自当地和全国各地的行业成员。该项目开发了一种低温（300 mK）一种扫描探针显微镜，在纳米级石英移液管的尖端上结合了SQUID传感器，满足了理解局部磁性和热材料特性。这种“SQUID-on-Tip”可用作磁力计、磁力计和温度计，其空间分辨率高达50 nm，单电子自旋磁灵敏度和微开尔文热灵敏度超过其他探头的热灵敏度。将这些功能结合在一台仪器中，可以进行许多其他仪器无法进行的研究。这台新仪器支持的研究项目包括拓扑超导体、马约拉纳费米子、拓扑保护磁孤子以及新型量子开关、人工工程热电、量子化热输运研究等。该项目是开发性的，因为没有商业上可获得的类似仪器。该项目的范围是实施SQUID的尖端传感器的制造技术，并将传感器在超低温扫描探针显微镜利用干燥的低温低温恒温器。传感器的制造需要一种新型的真空沉积系统，该系统允许在低温冷却的石英纳米移液管上热蒸发超导膜。扫描探针显微镜将商用定位载物台与SQUID-on-Tip传感器和相关电子设备集成在一起。项目范围包括使用磁或超导曲折或磁涡流进行显微镜验证的调试阶段。该项目的目标是为来自学术界、国家实验室和工业界的不同用户群提供对这种多功能仪器的协作访问。该奖项反映了NSF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。

Technological advances are increasingly dependent on the development of new materials, often requiring a deep understanding of their physical properties at the nanoscale. Traditional measurements of bulk or non-local quantities alone are insufficient. A new generation of instruments must be developed that can probe materials properties at nanometer length scales. However, at these scales, the strength of signals (e.g., electric, magnetic, or thermal) from these tiny regions is weak, so these instruments must also be extremely sensitive. This project supports development of a cryogenic scanning probe microscope based on a non-invasive superconducting quantum interference device (SQUID) sensor with ultra-high sensitivity to both magnetic and thermal properties. The specific nanoSQUID technology employed in this instrument, a SQUID at the tip of a nano-pipette, has application to a broad range of systems. The instrument enables materials research in superconductivity, nanomagnetism, spintronics, quantum information and computing, topological materials, and quantized thermal transport and dissipation mechanisms. The multi-function scanning probe microscope is developed through an interdisciplinary collaboration of faculty, staff, and students at the Denver and Boulder campuses of the University of Colorado. Its development trains a full-time graduate student and three undergraduate students in instrumentation, cryogenics, and multiple other physics and engineering topics under the mentorship of two senior faculty and two senior engineering staff with complementary areas of expertise. This instrument is part of a suite of nanospectroscopy tools in the Colorado Front Range that brings in a diverse user base of academics, national laboratory scientists, and industry members from the local area and across the country.This project develops a low-temperature (300 mK) scanning probe microscope incorporating a SQUID sensor on the tip of a nanoscale quartz pipette that meets a critical need in the understanding of local magnetic and thermal material properties. This "SQUID-on-Tip" operates as magnetometer, susceptometer, and thermometer with spatial resolution as good as 50 nm, single-electron-spin magnetic sensitivity, and micro-Kelvin thermal sensitivity, orders of magnitude beyond the thermal sensitivity of other probes. The combination of these capabilities in one instrument enables many studies that cannot be carried out by any other instrument. Research projects enabled by this new instrument include studies of topological superconductors, Majorana fermions, topologically protected magnetic solitons as well as novel quantum switches, artificially engineered thermoelectrics, studies of quantized thermal transport, and more. This project is developmental because no comparable instrument is available commercially. The project scope is to implement the fabrication technology of the SQUID-on-Tip sensor and to incorporate the sensor in an ultra-low-temperature scanning probe microscope utilizing a dry low-temperature cryostat. Fabrication of the sensor requires a novel vacuum deposition system that allows for thermal evaporation of a superconducting film on a cryogenically cooled quartz nano-pipette. The scanning probe microscope integrates commercial positioning stages with the SQUID-on-Tip sensor and associated electronics. The project scope includes a commissioning phase using magnetic or superconducting meanders, or magnetic vortices for microscope verification. The goal of this project is to provide collaborative access to this multi-function instrument to a diverse user base from academia, national laboratories, and industry.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.