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A method for detecting dc spin current propagation through an epitaxial antiferromagnetic (AFM) NiO layer is presented. Spin current is generated by spin pumping from an adjoining ferromagnetic (FM) layer and detected in a non-magnetic metallic layer by the inverse spin Hall effect. Comparison is made with a YIG/Pt bilayer, where only the Pt layer is electrically conducting, but for which spin Hall magnetoresistance makes an additional contribution to the measured signal. The signal obtained from the multilayered stack containing the AFM NiO layer is found to contain additional contributions due to anisotropic magnetoresistance. By exciting the sample with out-of-plane rf magnetic field and making measurements with a static field applied at different orientations within the plane of the sample, a signal associated with the dc spin current may be identified. [ABSTRACT FROM AUTHOR]

Tapered coplanar waveguides with integrated photoconductors were designed, fabricated, and measured, with pulsed transmission results comparing well with High Frequency Structure Simulator simulations which predict increased confinement and electric field concentration in the tapered region. Devices made with titanium/gold metallisation were used to demonstrate transmission and confinement, while the magnetoresistive properties of devices with cobalt/copper multilayers were used to demonstrate the field concentration. In the latter case, a mathematical framework was developed to understand the relationship between tapering effects and the picosecond magnetoresistance response. [ABSTRACT FROM AUTHOR]