CAREER: Skyrmion-Vortex Interactions in Ferromagnet-Superconductor Heterostructures

非技术摘要：自旋电子学领域是一个快速发展和颠覆性的研究领域，产生了上级于传统计算电子学的新型器件方案。 传统的电子元件使用电子电荷来存储和传输信息。举例来说，电容器上累积的电荷量可确定其贡献“0”还是“1”二进制数字。 另一方面，自旋电子器件利用电子的另一种属性，称为自旋（向上，向下或倾斜），来编码信息。 这些器件实际上可以使用自旋电流来控制逻辑操作，比在传统的基于半导体晶体管的逻辑中可以实现的充电电流更快且更节能。 自旋电子器件通常由作为自旋电流源的铁磁体组成。作为超导体的超导元件，没有电阻，可以提高整体器件性能并提供新的功能，例如非常低的耗散（能量损失）自旋传输。 这种铁磁超导体结构也是拓扑量子计算方案的组成部分，这种架构预计对困扰其他量子设备平台的环境噪声具有鲁棒性。 该项目研究铁磁超导体设备，通过对整个设备的纳米级磁场进行成像，并确定温度和施加电流对设备操作的影响，可以形成新型计算架构的构建模块。这一努力还有助于在美国发展具有全球竞争力的量子劳动力，方法是设计一门新颖的实验室课程，教授量子传感和计算职业的基础技能，并为当地小学的K-12学生提供电子培训。铁磁-超导体（FS）异质结构是超导自旋电子学和拓扑量子计算的有前途的平台。在FS异质结中，理论上预测可以形成计算应用所需的skyrmion-涡旋对。这个计划的目的是设计，制造和研究一个系统，其中skyrmions和旋涡共存和相互作用。具体来说，研究小组研究了两种不同FS异质结构中的邻近耦合：铁锗碲化物（FGT）-超导体双层和超导层下的FeGe岛阵列。对于这两种异质结构，他们采用磁力显微镜和电输运测量来研究在可变温度（低至1.6 K）和磁场（高达12 T）下这些器件中出现的磁性纹理的动力学，确定skyrmions和涡旋共存和结合的条件。建议的工作包括研究热能和电流感应力的影响，并将结果与描述skyrmion-vortex pair dynamics的半经典理论进行比较。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical abstract:The field of spintronics is a rapidly advancing and disruptive research area, producing novel device schemes that are superior to conventional computing electronics. Conventional electronic elements use electron charge to store and transmit information. For example, the amount of charge accumulated on a capacitor may determine whether it contributes a “0” or a “1” binary digit. On the other hand, spintronic devices exploit another property of electrons, called spin (up, down, or canted), to encode information. These devices can in fact use spin currents to control logic operations faster and more energy efficiently than charge currents can accomplish in conventional semiconductor transistor-based logic. Spintronics devices typically consist of ferromagnets as the source of the spin current. Incorporating elements that are superconductors, which have no electrical resistance, can enhance the overall device performance and offer new functionalities, such as remarkably low-dissipation (energy loss) spin transport. Such ferromagnetic-superconductor structures are also constituents of schemes for topological quantum computing, an architecture that is predicted to be robust to environmental noise that plagues other quantum device platforms. This project investigates ferromagnetic-superconductor devices that could form building blocks of novel computing architectures by imaging nanoscale magnetic fields throughout the device and determining the effects of temperature and an applied current on the device operation. This effort also contributes to the development of a globally competitive quantum workforce in the U.S. by designing a novel lab course that teaches foundational skills for careers in quantum sensing and computing, and providing training in electronics to K-12 students at a local elementary school. Technical abstract:Ferromagnet-superconductor (FS) heterostructures are promising platforms for superconducting spintronics and topological quantum computing. In FS heterostructures, it is theoretically predicted that skyrmion-vortex pairs can form that are desirable for computing applications. The objective of this program is to design, fabricate, and study a system in which skyrmions and vortices co-exist and interact. Specifically, the research team studies proximity coupling in two different FS heterostructures: iron germanium telluride (FGT) - superconductor bilayers and arrays of FeGe islands under a superconducting layer. For both heterostructures, they employ magnetic force microscopy and electrical transport measurements to study the dynamics of magnetic textures that emerge in these devices under variable temperatures (down to 1.6 K) and magnetic fields (up to 12 T), determining the conditions under which skyrmions and vortices co-exist and bind. Proposed work includes studies of the effects of thermal energy and current-induced forces, and comparing the results to semiclassical theories describing skyrmion-vortex pair dynamics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.