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

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设备。这项拟议工作的目标是提高一种非侵入性、高灵敏度的技术--扫描超导量子干涉装置(SQUID)磁感应强度测量的能力，以动态表征纳米磁系统和现象。主要研究人员将通过两项创新来实现这一目标。首先，自旋灵敏度将从当前技术水平的每Hz1/2几千个电子自旋提高到每Hz1/2几十个自旋。这一改进将通过减少光学和电子束组合光刻工艺中的拾取回路尺寸和利用超低噪声DC Squid工艺来实现。其次，通过使用DC Squid串联阵列放大器作为DC Squid电感的前置放大器，带宽将从当前技术水平的数十kHz增加到数十MHz，并将在4K和20mK下表征磁通灵敏度和带宽。这些器件在4K下将有许多应用，尽管在20MK下的工作对于研究电子系统中的量子退相干机制是必不可少的。本科生将与研究生在合作者的实验室中合作，通过对直径从3 nm到10 nm的单个钴纳米磁球成像，以及从数万到数万个电子自旋的磁矩，来表征设备的自旋敏感度及其在现实扫描条件下的性能。此外，一个SQUID磁感仪将用于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制造将在纳米结构、新现象和量子控制领域应用的传感器，并使用这些传感器成像单个钴纳米磁铁的静态和动态特性。将高灵敏度、高带宽的SQUID敏感仪集成到扫描平台中，将显著增加可研究的系统的数量和种类，减少周转时间，并增加可在单个实验中研究的样本数量。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。这一项目的另一个好处是CU-Denver(派的机构)和Stanford大学(合作者的机构)的教育好处，这是由CU-Denver本科生和斯坦福研究生之间的合作产生的。

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.