CAREER: Spin-Orbit Interaction based Spintronics with Superconductors

自旋电子器件利用电子的自旋自由度来存储和处理信息。自旋电子学研究的中心课题之一是控制电子自旋的方向。目前已经开发了各种机制来控制电子自旋（或等效的磁矩）的方向。然而，主要的障碍之一是所有这些机制都消耗大量的能量。在这项提案中，将努力集中在寻找用超导材料控制自旋的可能性，在那里能量消耗将最小化。对超导体内部自旋动力学的科学探索，不仅可以加深对超导体和自旋电子材料性质的认识，而且可以开发低功耗、快速度的存储和逻辑器件，这将大大推进现有的计算技术。同时，我们的研究和教学活动将通过各种推广计划，帮助提高社会对自旋电子材料和器件中一些最令人兴奋的新挑战的认识。具体来说，本提案旨在实验研究超导材料中自旋轨道相互作用引起的现象。该方案的中心目标包括探测超导体中自旋轨道相互作用诱导的自旋产生，并利用过量的自旋积累来激发相邻铁磁体中的磁动力学。这些目标将通过以下几个方面的实验活动来实现：首先，利用自旋极化隧道结、自旋轨道转矩铁磁共振等电测量技术来研究超导体中自旋轨道相互作用诱导的自旋产生。其次，在直流和交流两种情况下，确定超导体/铁磁界面处自旋轨道力矩的存在性和性质。设备几何形状，如自旋泵和霍尔棒磁力计将被采用。第三，通过理论和实验研究非耗散和耗散自旋轨道转矩的能量转换机制。最后，基于超导自旋轨道相互作用效应的自旋电子器件将被制造出来。特别是，超导体携带的电流将用于切换纳米级铁磁体的取向。通过这些努力，预计将展示低功耗、低温存储和逻辑功能，这将对正在进行的基于低温超导体的高性能计算机的开发非常有用。

Spintronic devices utilize electrons' spin degree of freedom to store and process information. One of the central topics in spintronic study is to manipulate the orientation of electron spins. Currently various mechanisms have been developed to control the direction of electrons' spin (or equivalently, magnetic moment). However, one of the major obstacles is that all of these mechanisms consume significant amount of power. In this proposal, efforts will be focused on looking into the possibility of controlling spins with superconducting materials, where the energy consumption will be minimized. The scientific exploration of the spin dynamics inside the superconductors will not only deepen understanding about the properties of superconductor and spintronic materials, but also allow for the development of low power consumption, fast speed memory and logic devices which will greatly advance existing computation technologies. In the meantime, the proposed research and teaching activities will help to increase society's awareness on some of the most exciting new challenges in spintronic materials and devices through various outreach programs.Specifically, this proposal aims to experimentally investigate spin orbit interaction induced phenomena in superconducting materials. The central objectives of the proposal include probing the spin orbit interaction induced spin generation in superconductors and utilizing the excessive spin accumulations to excite magnetic dynamics in adjacent ferromagnets. These goals will be realized through experimental activities in the following aspects: first of all, the spin orbit interaction induced spin generation in superconductors will be examined with the electrical measurement techniques such as spin polarized tunnel junction, spin orbit torque ferromagnetic resonance, etc. Secondly, the existence and the nature of spin orbit torques at superconductor/ferromagnet interface will be determined and quantified both in the DC and AC regime. Device geometries such as spin pumping and Hall bar magnetometer will be employed. Thirdly, the energy conversion mechanism associated with the non-dissipative and dissipative spin orbit torques will be looked into through theoretical and experimental investigations. Finally, spintronic devices based upon effects originated from superconducting spin orbit interaction will be fabricated. Particularly, current carried by superconductors will be used to switch the orientation of nanoscale ferromagnet. Through these efforts, it is expected that low power, cryogenic temperature memory and logic functions will be demonstrated, which will be highly useful for the ongoing development of low temperature superconductor based high performance computers.