|Keller, Mark William
|Silva, Thomas J.
A variety of spintronic device proposals are based on pure spin currents flowing in bulk materials and across interfaces between different materials. While a robust understanding of charge currents in semiconductors, metals, and insulators enables accurate models of electronic devices at nanometer length scales and picosecond time scales, our understanding of spin currents is much less developed. Spin transport in ferromagnetic (FM) materials, non-magnetic (NM) materials, and across FM/NM interfaces involves phenomena with no analog in charge transport, such as the torque exerted on a FM layer with it absorbs a spin current. In materials with strong spin-orbit interactions, spin Hall and related effects cause spin and charge current interconversion, adding further complexity. Detecting and accurately quantifying spin transport and spin-charge interconversion is a rich and important measurement science problem for spintronics. We employ state-of-the-art ferromagnetic resonance spectroscopy, Brillouin light scattering, magneto-optical Kerr microscopy, and other techniques to address this challenge. With collaborators at universities and national facilities such as synchrotrons, we also use x-ray techniques to obtain images of magnetic structure and measure ultrafast spin dynamics of FM and NM materials. We have several chambers for sputter deposition of multilayer stacks and a clean room for fabricating a variety of device structures.
Humphries, A. M., et al. (2017). "Observation of spin-orbit effects with spin rotation symmetry." Nat. Commun. 8(1): 911.
Berger, A. J., et al. (2018). "Inductive detection of fieldlike and dampinglike ac inverse spin-orbit torques in ferromagnet/normal-metal bilayers." Phys. Rev. B 97(9): 094407.
Berger, A. J., et al. (2018). "Determination of the spin Hall effect and the spin diffusion length of Pt from self-consistent fitting of damping enhancement and inverse spin-orbit torque measurements." Phys. Rev. B 98(2): 024402.
Spin Hall effect; Spin orbit torques; Spintronics; Nanofabrication; Ferromagnetic resonance