NER: High-Bandwidth Scanning DC SQUID Susceptometer for Characterization of Nanomagnetic Structures and Phenomena

NER：用于表征纳米磁性结构和现象的高带宽扫描直流 SQUID 感受器

• 批准号: 0210877
• 负责人: Martin Huber
• 金额: $ 9.99万
• 依托单位: University of Colorado at Denver-Downtown Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-08-01 至 2004-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0210877&HistoricalAwards=false
• 关键词: NER; Bandwidth; Scanning; DC; SQUID

0210877HuberNanomagnetic devices for applications such as quantum computing and high-capacity memory cannot be developed without faster, more sensitive characterization tools to directly probe phenomena and material structures at the nanoscale. The objective of the proposed work is to advance the capability of a non-invasive, high-sensitivity technique-scanning superconducting quantum interference device (SQUID) susceptometry for the dynamic characterization of nanomagnetic systems and phenomena.The principal investigator will achieve this objective through two innovations. First, spin sensitivity will be improved from the current state of the art, a few thousand electron spins per Hz1/2, to a few tens of spins per Hz1/2. This improvement will be accomplished by reduction of pickup loop dimensions in a combined optical and electron-beam lithography process and by utilizing an ultra-low-noise dc SQUID process. Second, bandwidth will be increased from the current state of the art, tens of kHz, to tens of MHz by the use of dc SQUID series array amplifiers as preamplifiers for the dc SQUID susceptometer.The devices will be characterized for flux sensitivity and bandwidth at 4 K and 20 mK. The devices will have many applications at 4 K, although operation at 20 mK will be essential for the study of quantum decoherence mechanisms in electronic systems. Undergraduates, working with graduate students in the collaborator's laboratory, will characterize the spin sensitivity of the devices and their performance under realisticscanning conditions by imaging individual cobalt nanomagnetic spheres of controlled diameters ranging from 3 nm to 10 nm and magnetic moments ranging from tens to tens of thousands of electron spins. Further, one SQUID susceptometer will be used to image a second, identical device to quantitatively characterize the noise generated by the devices.The scientific emphasis of this project is to produce sensors that will have applications in the area of nanoscale structures, novel phenomena, and quantum control and to use these sensors image both static and dynamic properties of individual cobalt nanomagnets. Integration of a high-sensitivity, high-bandwidth SQUID susceptometer into a scanning platform will significantly increase the number and kind of systems that can be studied, decrease turn-around time, and increase the number of samples that can be studied in ansingle experiment. Thus, the successful realization of this project will contribute to advances in nanoscale devices and system architecture. An added benefit of this project will be the educational benefits at both CU-Denver (PI's institution) and Stanford University (collaborator's institution) resulting from the collaboration between CU-Denver undergraduate students and Stanford graduate students.

如果没有更快、更灵敏的表征工具来直接探测纳米级的现象和材料结构，就无法开发用于量子计算和大容量存储器等应用的纳米磁性器件。这项工作的目标是提高一种非侵入性的、高灵敏度的技术--扫描超导量子干涉仪（SQUID）的能力，用于纳米磁性系统和现象的动态表征。主要研究者将通过两项创新来实现这一目标。首先，自旋灵敏度将从现有技术的每Hz 1/2几千个电子自旋提高到每Hz 1/2几十个自旋。这种改进将通过减少光学和电子束光刻工艺组合中的拾取回路尺寸以及利用超低噪声直流SQUID工艺来实现。第二，通过使用直流SQUID系列阵列放大器作为直流SQUID磁强计的前置放大器，带宽将从当前技术水平的几十kHz增加到几十MHz。该器件将在4 K和20 mK下表征通量灵敏度和带宽。 该设备将在4 K下有许多应用，尽管在20 mK下的操作对于研究电子系统中的量子退相干机制至关重要。 本科生与合作者实验室的研究生一起工作，将通过对单个钴纳米磁性球体进行成像来表征设备的自旋灵敏度及其在真实扫描条件下的性能，这些球体的可控直径范围从3 nm到10 nm，磁矩范围从数十到数万个电子自旋。此外，一个SQUID温度计将被用来成像第二个，相同的设备，以定量表征设备产生的噪声。该项目的科学重点是生产的传感器，将在纳米结构，新现象，量子控制领域的应用，并使用这些传感器图像的静态和动态特性的单个钴纳米磁体。 将高灵敏度、高带宽SQUID温度计集成到扫描平台中将显著增加可以研究的系统的数量和种类，减少周转时间，并增加在单个实验中可以研究的样品数量。因此，该项目的成功实现将有助于纳米器件和系统架构的进步。该项目的另一个好处是，丹佛大学（PI的机构）和斯坦福大学（合作者的机构）的教育效益将来自丹佛大学本科生和斯坦福大学研究生之间的合作。