Hall effect due to spin injection in Co/Al planar junctions

The Hall effect due to spin injection was investigated by using an Al Hall bar attached to a Co/Al planar wire junction. There is observed a significa nt change in the Hall voltage due to the spin injection when the position o f the Hall bar is placed 0.5 mu m away from the Co/Al interface. The obtain ed results were analyzed by taking into account the contributions of the en hancement of the ordinary Hall effect due to a locally increased gradient o f the electrochemical potential, and of the extraordinary Hall effect due t o the induced nonequilibrium magnetization. The spin diffusion length in Al in the present study is about 1 mu m, and the induced difference in chemic al potential between up and down spins is about 2.6x10(-8) eV. The experime ntally evaluated enhancement factor of the ordinary Hall effect is about 1. 5, which shows a relatively small contribution to the net Hall effect compa red to the extraordinary Hall effect due to the induced nonequilibrium magn etization. (C) 2000 American Institute of Physics. [S0021-8979(00)56208-2].