Magnetic Skyrmion for Nonvolatile Low-Power Spin-Orbitronics Applications

该提案旨在解决互补金属氧化物半导体（CMOS）的缩放相关的挑战性问题：功耗和可变性。为了实现这一目标，拟议的研究探索的可能性，建立磁存储设备的基础上磁skyrmions为室温应用具有非易失性，高密度和低功耗。磁skyrmion是一种粒子状的，拓扑保护的磁畴。作为非易失性信息载体，存储器件中的每个单个Skyrmion由于其小尺寸、低驱动电流密度和额外的拓扑保护而能够实现高密度、低功率操作。本研究将建立一个以拓扑保护自旋织构为信息载体的磁存储器件框架。这种影响将是变革性的，从而使新型磁存储器的构建成为可能。高密度存储器将有助于加速大数据和物联网时代的进步。同时，当与CMOS半导体技术集成时，它可能解决能量耗散的挑战，从而进一步推进技术节点。此外，这种跨学科的研究也具有巨大的教育影响，因为来自自旋轨道耦合工程的新知识将对新生产生新的教育意义。从高中到本科/研究生的教育水平的学生，以及博士后（包括女性和少数民族）将通过PI参与加州大学洛杉矶分校的高中和新生外展计划，在物理科学和工程以及计算机科学的跨学科和多学科新兴领域进行接触和培训。在这些新兴学科的学生的培训将提供多样化的人力资本，精通科学方法和应用经验。教育的影响是进一步扩大目前的推广计划，通过加州纳米系统和国家科学基金会-ERC的翻译应用的纳米多铁性Systems.Although skyrmions可以固有地存在于一组所谓的helmagnetic材料（B-20）化合物，skyrmions在磁性多层膜或接口将更兼容现有的磁记录/存储技术。因此，拟议的项目侧重于研究在铁磁层/重材料（FM/HM）薄膜系统的skyrmion创建，操纵和检测。该系统提供了最大程度地调整和调谐skyrmion属性以用于应用目的的可能性。单个Skyrmions的创建和湮灭将在实验上实现，并在理论上进行动态和静态分析。相对论自旋轨道耦合（SOC）产生的自旋轨道力矩可以控制电流对Skyrmions的操纵。每个单独的skyrmion可以通过磁隧道结使用磁阻效应来检测。单Skyrmions的单自旋织构将通过微磁模拟建模。 从这项研究中学到的知识和经验将使信息的电编码和解码成为可能;在这项研究中使用具有低温工艺的常用薄膜材料系统自动确保设备与当前的CMOS或磁记录技术完全兼容。这项研究具有革命性，因为它调用了许多独特的创新，包括（1）FM/HM异质结构中的界面Dzyaloshinskiii-Moriya相互作用，以创建具有可控尺寸的skyrmion;（2）通过FM/HM界面处的电流诱导自旋轨道扭矩有效地操纵skyrmion运动;（3）使用高质量MTJ进行信息编码和检测;（4）纳米结构工程和压控磁各向异性（VCMA）。

This proposal aims to resolve the challenging issues related to the scaling of complementary metal-oxide-semiconductor (CMOS): power dissipation and variability. To achieve this goal, the proposed research explores the possibilities to build magnetic memory devices based on magnetic skyrmions for room-temperature applications featuring in nonvolatile, high density and low-power consumption. A magnetic skyrmion is a particle-like, topologically protected magnetic domain. As a nonvolatile information carrier, each individual skyrmion in a memory device can enable high-density, low-power operations due to the small size, the low driving current density and the extra topological protection. The proposed research will establish a framework for magnetic memory devices using topologically protected spin texture as the information carrier. The impact will be transformative and thus enables the construction of novel magnetic memory. The high-density memory will help accelerate the progress of the big data and internet-of-things era. Meanwhile, when integrated with the CMOS semiconductor technology, it potentially resolves the energy dissipation challenge and thus further advances the technology node. Additionally, this interdisciplinary research also has a vast educational impact, as the new knowledge from the spin orbit coupling engineering will have emerging educational meaning for new students. Students with education level from high school to undergraduate/graduate students, and postdocs (including women and minorities) will be exposed and trained in this inter- and multi-disciplinary and emerging fields of physical science and engineering as well as computer science through PI's participation of the high school and freshman outreach programs at UCLA. The training of students in these emerging disciplines will provide diverse human capital, versed in scientific method and experienced in the applications. The educational impact is further amplified by current outreach programs through the California NanoSystems and the NSF-ERC on Translational Applications of Nanoscale Multiferroic Systems.Although skyrmions can intrinsically exist in a group of so-called helimagnetic materials (B-20) compounds, skyrmions in magnetic multilayers or interfaces will be more compatible with existing magnetic recording/memory technologies. Thus, the proposed project focuses on the study of skyrmion creation, manipulation and detection in ferromagnetic layer/heavy-material (FM/HM) thin-film systems. This system provides the possibility to furthest adjust and tune the skyrmion properties for application purposes. The creation and annihilation of single, individual skyrmions will be experimentally realized and theoretically analyzed dynamically and statically. The manipulation of skyrmions can be controlled by currents via spin-orbit torque coming from the relativistic spin-orbit coupling (SOC). Each individual skyrmion can be detected using magnetoresistance effect via magnetic tunnel junctions. Single spin textures of single Skyrmions will be modeled via micromagnetic simulation. Knowledge and experience learnt from this study will enable electrically encoding and decoding of information; the use of commonly accessible thin film material systems with low-temperature process in this research automatically ensures devices to be fully compatible with current CMOS or magnetic recording technology. The proposed research is transformative since it invokes many unique innovations from (1) interfacial Dzyaloshinskii-Moriya interaction in FM/HM heterostructures to create skyrmion with controllable sizes; (2) effectively manipulation of skyrmion motion by the current-induced spin-orbit torque at the FM/HM interface; (3) the use of high-quality MTJ for information encoding and detection; (4) nanostructure engineering and voltage-controlled magnetic anisotropy (VCMA).