(a) Schematic diagram of spin-valve device structure as fabricated on -type InAs, magnetoresistance measurement configuration, and InAs electronic structure. (b) Schematic diagram of Corbino disk device structure, measurement configuration, and InAs electronic structure.
Topographic and conductive atomic force microscope images, obtained simultaneously in each case with 1 V bias applied to the sample, of (a) -type InAs with native oxide layer and (b) -type InAs on which a 3 nm layer have been deposited by sputtering. All scale bars are 200 nm. Gray scales correspond to 5 nm for topography, and 1 nA for current.
(a) Magnetoresistance measured for spin-valve device structure shown in Fig. 1(a), for field sweep directions from − to (open circles) and from to − (solid squares). (b) Maximum measured magnetoresistance as a function of spin-valve channel length (filled squares), along with curve fitted according to Eq. (1) from which the spin injection efficiency and spin diffusion length are determined.
(a) Schematic diagram of measurement process for atomic and magnetic force microscopy of Co ferromagnetic contacts for spin-valve device. (b) Topographic image of Co contacts and [(c)–(e)] magnetic force images of Co contacts after application of external magnetic fields of 300, 600, and 1200 Oe, respectively. The magnetic force images show the transition from parallel magnetization, in (c), to antiparallel magnetization, in (d), and back to parallel magnetization, in (e), in the opposite direction to that in (c). All scale bars are 500 nm. Gray scale corresponds to 300 nm in topographic image. The dashed outlines indicate the edges of the Co contacts. The magnetization direction of each Co contact is indicated by arrows.
Magnetoconductance measured in Corbino disk device structure shown in Fig. 1(b), along with fitted curves from ILP theory, for (a) Corbino disk device with native oxide on InAs surface and (b) Corbino disk device with sulfur-passivated InAs surface.
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