Renewal IRG Talk: Zeke Johnston-Halperin, “Thermal and coherent excitation of dynamically driven spin currents”

 Summary:Recent years have seen dramatic advances in the emerging fields of thermally driven spin currents and the use of ferromagnetic resonance (FMR) to drive spin transfer across magnetic/non-magnetic interfaces. There is an emerging consensus that these two phenomena arise from the same underlying mechanism wherein dynamic magnetic excitations give rise to the generation of both DC and dynamically varying spin currents. However, the theoretical models that have been developed to date lack a detailed explanation of the coupling between the dynamic magnetic excitations of the magnetic material and the resulting spin excitations in the adjacent non-magnetic layer. In addition, these models fail to explain critical features of the experimental observations. Specific examples include the observation of a giant spin-Seebeck effect (SSE) in non-magnetic InSb, the symmetry and angular dependence of FMR-driven spin pumping, and the observation of spin pumping across insulating tunnel barriers and spacers. In this IRG proposal, we leverage unique expertise in both thermal and FMR driven spin physics to develop a coordinated program aimed at developing a comprehensive understanding of this novel class of phenomena. We have assembled a diverse and interdisciplinary team with expertise in materials synthesis, state of the art experimental techniques and cutting edge theory and modeling and have identified a synergistic portfolio of projects targeting topics such as the relative roles of spin drift, spin diffusion and spin pumping in the spin-transfer process, the role of the magnetic/non-magnetic interface and concurrent dissipation, and the length scales of this dynamic coupling. We anticipate that this coordinated approach will build on our existing, world leading, strengths to provide new insights and emergent science in this rapidly evolving field.

This talk is one of several presentations by prospective IRGs for the MRSEC Renewal. The intention of these presentations is to help teams identify and recruit key team members, and provide feedback on the proposed project goals, scientific approach, and team composition.

More information on the process for the renewal proposal can be found here.