Nonlocal electrical detection of spin accumulation generated by Anomalous Hall effects in mesoscopic Ni_81Fe_19 films

Spin accumulation generated by the anomalous Hall effects (AHE) in mesoscopic ferromagnetic Ni81Fe19 (permalloy or Py) films is detected electrically by a nonlocal method. The reciprocal phenomenon, inverse spin Hall effects (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 nm, 8 nm, 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.