We report studies of angular momentum transport between spatially distinct spin systems in various contexts. Microscopic studies allow material interfaces to be avoided by using magnetic field gradients to separate spatial regions. Scanned probe electron spin resonance studies of spin dynamics in nanostructured volumes of diamond containing nitrogen impurities reveal the impact of spin transport on spin dynamics within confined volumes. In addition to enabling imaging of nanoscale properties of buried ferromagnets, scanned probe ferromagnetic resonance offers an approach to studying dynamics in a continuous ferromagnet and spin transport between distinct regions defined by an intense, localized magnetic field. In bilayers we have systematically studied the magnitude of ISHE in various 3d and 5d metals and find that the impact of d-orbital filling on ISHE is surprisingly strong: comparable to atomic number. We have also studied the dependence of spin transport on the magnetic nature of diverse intervening layers; we find that antiferromagnetic intervening layers are efficient spin transporters at nm-scale thicknesses and the spin decay length is found to increase with the strength of AF coupling. We will also discuss optical techniques that provide a new approach to broadband, spatially resolved FMR detection for these and related studies.
This research is supported by the U.S. DOE through Grant No. DE-FG02-03ER46054 and DE-SC0001304, by the NSF through Grant No. 1420451 and by the Army Research Office through Grant W911NF0910147.