Investigation of Nanoscale Spin Dynamics with Scanning Probes

“该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。“这项提案将研究自旋扭矩引起的开关和铁磁共振动力学的小图案磁性隧道结器件使用扫描探针显微镜在几种模式。扫描探针将用于辅助尺寸在10 nm和1 μ m之间的器件的图案化。此外，正如之前在NSF资助下所展示的那样，扫描探针将用于对以这种方式制造的器件进行电气测量。将使用和进一步开发定制探头，用于提供开关所需的高电流和测量高达10 GHz的FMR。这项工作的样品将通过与Everspin技术合作提供。我们的目标将是量化的大小和形状的设备中的子100纳米范围内的作用，在确定开关的临界电流和自旋扭矩引起的共振的发病。这些结果将应用于存储器以及自旋扭矩振荡器设备在积极规模化的技术。在这项工作中提出的方法提供了几个优点的自旋扭矩驱动设备的制造和表征。最重要的是，使用探针进行测试极大地简化了制造挑战，降低了所需的图案化纵横比，并消除了引线和平面化需求。其次，用探针进行图案化可以用成本和复杂性适中的设备制造非常小的特征，放大了这项工作资助的一名研究生的活动。最后，扫描探针的几何形状可以快速测试许多设备，以评估分布和统计，这将是中央的自旋扭矩驱动的存储器和振荡器应用程序的设备的成功。技术优点：这项工作的技术优点是，它提供了评估模式自旋扭矩设备之间的DC和RF相互作用的能力，以及这些值的传播。更清楚地理解和量化这些分布将使密集阵列的存储器设计没有不可接受的相互作用，或者，相反，振荡器阵列的相互作用足够强，以促进许多设备耦合在一起和大功率输出。 这将推动我们沿着发展的自旋扭矩增益介质，或？史威瑟？，如Luc Berger所创造的，其在RF通信中具有巨大的应用。我们正在采取一种新的方法，我们试图耦合离散振荡元件与静磁相互作用，而不是连续的薄膜，试图进一步扩展系统的允许模式。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方面是我们将开展的计划外展活动。这个团队中的PI在与大学生一起构建工件方面有着良好的记录。我们将专注于实现第一代CMOS-MEMS扫描探针显微镜芯片。要做到这一点，我们将招募一个小团队的本科生设计和原型CMOS-MEMS扫描探针显微镜适合部署在教室里。虽然雄心勃勃，但我们相信这是相当容易处理的适度成本和复杂性，并将为ECE和物理本科生提供一个很好的学习机会。

"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.