  Spin Hall effect, one of the cornerstones in spintronics refers to the
emergence of an imbalance in the spin density transverse to a charge flow in a
sample under voltage bias. This study points to a novel way for an ultrafast
generation and tuning of a unidirectional nonlinear spin Hall current by means
of subpicosecond laser pulses of optical vortices. When interacting with
matter, the optical orbital angular momentum (OAM) carried by the vortex and
quantified by its topological charge is transferred to the charge carriers. The
residual spin-orbital coupling in the sample together with confinement effects
allow exploiting the absorbed optical OAM for spatio-temporally controlling the
spin channels. Both the non-linear spin Hall current and the dynamical spin
Hall angle increase for a higher optical topological charge. The reason is the
transfer of a higher amount of OAM and the enhancement of the effective
spin-orbit interaction strength. No bias voltage is needed. We demonstrate that
the spin Hall current can be all-optically generated in an open circuit
geometry for ring-structured samples. These results follow from a full-fledged
propagation of the spin-dependent quantum dynamics on a time-space grid coupled
to the phononic environment. The findings point to a versatile and controllable
tool for the ultrafast generation of spin accumulations with a variety of
applications such as a source for ultrafast spin transfer torque and charge and
spin current pulse emitter.
