Nonlocal electrical detection of spin accumulation generated by anomalous Hall effect in mesoscopic Ni81Fe19 films

Spin accumulation generated by the anomalous Hall effect (AHE) in mesoscopic ferromagnetic Ni81Fe19 (permalloy, Py) films is detected electrically by a nonlocal method. The reciprocal phenomenon, the inverse spin Hall effect (ISHE), can also be generated and detected all electrically in the same structure. For accurate quantitative analysis, a series of nonlocal AHE/ISHE structures and supplementary structures are fabricated on each sample substrate to account for statistical variations and to accurately determine all essential physical parameters in situ. By exploring Py thicknesses of 4, 8, and 12 nm, the Py spin diffusion length lambda(Py) is found to be much shorter than the film thicknesses. The product of lambda(Py) and the Py spin Hall angle alpha(SH) is determined to be independent of thickness and resistivity: alpha(SH)lambda(Py) = (0.066 +/- 0.009) nm at 5 K and (0.041 +/- 0.010) nm at 295 K. These values are comparable to those obtained from mesoscopic Pt films.