  The spin Hall effect in tungsten films has been experimentally studied by
using STM-based measurements. These measurements have been performed by using
tungsten and iron coated tungsten tips. In the case of tungsten tips, it has
been observed that the current flow through the tungsten film results in an
appreciable asymmetry in the tunneling current with respect to the change in
the polarity of the tunneling voltage. It is reasoned that the cause of this
asymmetry is the accumulation of spin polarized electrons on the tungsten film
surface due to the spin Hall effect. This asymmetry is not affected by the
change of the direction of the bias current through the film. However, in the
case of iron coated tungsten tips, it has been observed that a change in the
direction of the bias current does lead to an additional asymmetry in the
tunneling current. It is thus experimentally demonstrated that this asymmetry
is caused by the SHE and spin-dependent density of states of iron-coated tips.
