  We reveal the giant magnetoresistance induced by the spin-polarized current
in the ferromagnet (F_1)/topological insulator (TI)/ferromagnet (F_2) junction,
where two ferromagnets are deposited on the diffusive surface of the TI. We can
increase and reduce the value of the giant magnetoresistance by tuning the
spin-polarized current, which is controlled by the magnetization
configurations. The property is intuitively understood by the non-equilibrium
spin-polarized current, which plays the role of an effective electrochemical
potential on the surface of the TI.
