  Spin diffusion length of Pt is evaluated via proximity effect of spin orbit
coupling (SOC) and anomalous Hall effect (AHE) in Pt/Co2FeAl bilayers. By
varying the thicknesses of Pt and Co2FeAl layer, the thickness dependences of
AHE parameters can be obtained, which are theoretically predicted to be
proportional to the square of the SOC strength. According to the physical image
of the SOC proximity effect, the spin diffusion length of Pt can easily be
identified from these thickness dependences. This work provides a novel method
to evaluate spin diffusion length in a material with a small value.
