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.
