  In the field of spintronics the "conductivity mismatch" problem remains an
important issue. Here the difference between the resistance of ferromagnetic
electrodes and a (high resistive) transport channel causes injected spins to be
backscattered into the leads and to lose their spin information. We study the
effect of the resulting contact induced spin relaxation on spin transport, in
particular on non-local Hanle precession measurements. As the Hanle line shape
is modified by the contact induced effects, the fits to Hanle curves can result
in incorrectly determined spin transport properties of the transport channel.
We quantify this effect that mimics a decrease of the spin relaxation time of
the channel reaching more than 4 orders of magnitude and a minor increase of
the diffusion coefficient by less than a factor of 2. Then we compare the
results to spin transport measurements on graphene from the literature. We
further point out guidelines for a Hanle precession fitting procedure that
allows to reliably extract spin transport properties from measurements.
