  We theoretically study spin and charge transport induced by a twisted light
beam irradiated on a disordered surface of a doped three dimensional
topological insulator (TI). We find that various types of spin vortices are
imprinted on the surface of the TI depending on the spin and orbital angular
momentum of the incident light. The key mechanism for the appearance of the
unconventional spin structure is the spin-momentum locking in the surface state
of the TI. Besides, the diffusive transport of electrons under an inhomogeneous
electric field causes a gradient of the charge density, which then induces
nonlocal charge current and spin density as well as the spin current. We
discuss the relation between these quantities within the linear response to the
applied electric field using the Keldysh-Green's function method.
