Effective nonlocal spin injection through low-resistance oxide junctions

Abstract

Many (>40) nonlocal spin valves on the same substrate have been characterized at 6K and 295K by using a probe station. Low-resistance oxide junctions (0.2–0.8Ω) are used to inject spin current into mesoscopic Cu channels. Spin signals exceeding 10mΩ at 6K have been consistently observed, indicating efficient spin injection and detection. However, complex switching behavior and possible variations between devices pose a challenge to using a standard fitting method to quantify the spin signals. Two methods are used for quantitative analysis. The range of the effective spin polarizations can be estimated by assuming a reasonable range for the Cu spin diffusion lengths. A nonlocal spin polarization is introduced to evaluate the spin current in the Cu channels.