  There exists considerable confusion in estimating the spin diffusion length
of materials with high spin-orbit coupling from spin pumping experiments. For
designing functional devices, it is important to determine the spin diffusion
length with sufficient accuracy from experimental results. An inaccurate
estimation of spin diffusion length also affects the estimation of other
parameters (e.g., spin mixing conductance, spin Hall angle) concomitantly. The
spin diffusion length for platinum (Pt) has been reported in literature in a
wide range of 0.5 - 14 nm, and particularly it is a constant value independent
of Pt's thickness. Here, the key reasonings behind such wide range of reported
values of spin diffusion length have been identified comprehensively.
Particularly, it is shown here that a thickness-dependent conductivity and spin
diffusion length is necessary to simultaneously match the experimental results
of effective spin mixing conductance and inverse spin Hall voltage due to spin
pumping. Such thickness-dependent spin diffusion length is tantamount to
Elliott-Yafet spin relaxation mechanism, which bodes well for transitional
metals. This conclusion is not altered even when there is significant
interfacial spin memory loss. Furthermore, the variations in the estimated
parameters are also studied, which is important for technological applications.
