Investigation of Nanoscale Spin Dynamics with Scanning Probes

“该奖项由2009年美国复苏和再投资法案(公法111-5)资助。”这项提议将使用扫描探针显微镜以几种方式研究小型图案化磁性隧道结器件的自旋扭矩感应开关和铁磁共振动力学。扫描探头将被用来帮助对尺寸在10 nm到1&amp；m之间的设备进行图案化。此外，正如之前在NSF资助下展示的那样，扫描探头将用于对以这种方式制造的设备进行电学测量。为提供开关所需的高电流和测量高达10 GHz的FMR而开发的定制探头将被使用和进一步开发。这项工作的样本将通过与EverSpin技术公司的合作提供。我们的目标将是量化100 nm以下器件的尺寸和形状在确定开关的临界电流和自旋扭矩诱导的共振开始时所起的作用。这些结果将应用于存储器以及大规模技术中的自旋扭矩振荡器设备。这项工作提出的方法为自旋扭矩驱动器件的制造和表征提供了几个优点。最重要的是，使用探头进行测试大大简化了制造挑战，降低了所需的图案化纵横比，并消除了引线和平坦化的需要。其次，带有探头的图案允许用成本和复杂性适中的设备制造非常小的特征，放大了一名研究生的活动，该研究生将由这项工作资助。最后，扫描的探头几何形状可以快速测试许多设备，以评估分布和统计，这将是自旋扭矩驱动设备成功应用于存储器和振荡器的关键。技术优点：这项工作的技术优点是，它提供了评估图案化自旋扭矩设备之间的DC和RF相互作用以及这些值的传播的能力。更清楚地了解和量化这些分布将能够设计密集的存储器阵列，而不会产生不可接受的相互作用，或者相反，具有足够强的相互作用的振荡器阵列将有助于将许多设备耦合在一起和大功率输出。这将推动我们开发一种自旋扭矩增益介质，或称SWASER，由Luc Berger发明，在射频通信中有巨大的应用。我们正在采取一种新的方法，试图将离散的振荡元件与静磁相互作用相结合，而不是连续的薄膜，试图进一步量化系统允许的模式。更广泛的影响：这项工作的更广泛的影响有两个方面。首先是我们强大的产业互动。EverSpin正在密切关注这项工作，因为它直接关系到他们可能开发的未来几代技术。这项工作的更广泛影响的第二个层面是我们将开展的有计划的外联活动。这个团队中的PI有一个与本科生一起构建人工制品的经过证明的记录。我们将专注于在芯片上实现第一代CMOS-MEMS扫描探针显微镜。为了做到这一点，我们将招募一个本科生小组来设计和制作一种适合在课堂上部署的CMOS-MEMS扫描探针显微镜的原型。虽然雄心勃勃，但我们相信，由于成本和复杂性不高，这是相当容易处理的，并将为欧洲经委会和物理学本科生提供一个极好的学习机会。

"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."This proposal will investigate the spin torque induced switching and ferromagnetic resonance dynamics of small patterned magnetic tunnel junction devices using scanning probe microscopy in several modalities. Scanning probes will be used to assist in the patterning of devices between 10 nm and 1 μm in size. Additionally, as previously demonstrated under NSF funding, scanning probes will be used to make electrical measurements on devices fabricated in this way. Custom probes developed for the delivery of the high currents needed for switching and for making measurements of FMR up to 10 GHz will be used and further developed. Samples for this work will be provided through collaboration with Everspin Technologies. The goal will be to quantify the role of size and shape of devices in the sub-100 nm range in determining critical current for switching and the onset of spin-torque induced resonance. These results will have application to memory as well as spin-torque oscillator devices in aggressively scaled technologies. The approach proposed in this work offers several advantages for the fabrication and characterization of spin-torque driven devices. Most importantly, testing with probes dramatically simplifies the fabrication challenges, reducing the patterning aspect ratio that is required, as well as eliminating leads and the need for planarization. Secondly, patterning with probes allows for very small features to be made with equipment of modest cost and complexity, amplifying the activities of the one graduate student who would be funded by this work. Finally, the scanned probe geometry can quickly test many devices to assess distributions and statistics, which will be central to success of spin torque driven devices both for memory and oscillator applications.Technical Merit: The technical merit of this work is that it offers the ability to assess both DC and RF interactions among patterned spin torque devices, and the spread of these values. Clearer understanding and quantification of these distributions will enable the design of dense arrays for memory without unacceptable interactions, or, conversely, arrays of oscillators with interactions sufficiently strong to facilitate the coupling of many devices together and large power outputs. This will move us along on the development of a spin torque gain medium, or ?swaser?, as coined by Luc Berger, with enormous application to RF communications. We are taking a novel approach where we attempt to couple discrete oscillating elements with magnetostatic interactions, rather than continuous films to attempt to further quantize the allowed modes of the system.Broader Impact: The broader impact of this work has two aspects. First is our strong industrial interaction. Everspin is following this work closely as it bears directly on future generations of technology they might develop. A second dimension of this broader impact of this work is the planned outreach activities that we will undertake. The PIs in this team have a proven track record working with undergraduates building artifacts. We will focus on implementing a first generation CMOS-MEMS scanned probe microscope on a chip. To do this we will enlist a small team of undergrads to design and prototype a CMOS-MEMS scanned probe microscope suitable for deployment in a classroom. While ambitious, we believe this is quite tractable for modest cost and complexity and will present an excellent learning opportunity for ECE and Physics undergraduates.