  Spin-dependent diffraction occurs in helimagnet-related transport processes.
In this work, we investigated quantum pumping properties in the
normal-metal/helimagnet/normal-metal heterostructure driven by two out of phase
time-dependent gate potentials. At the condition when one of the diffracted
beams goes out of the horizon the pumped charge and spin currents demonstrate
sharp dips and rises as a function of the helimagnet spiral wavevector $q$. At
small and large $q$'s, the transmission and pumping properties approach the
behaviors of a ferromagnet and an insulating barrier, respectively. For
different helimagnet spiral periods, the diffracted angles are different. As a
result, the pumped charge and spin currents demonstrate multiple maximal and
minimal peaks as a function of $q$, hence, sensitively depend on the helimagnet
spin configuration. All the pumping properties can be interpreted by the
quantum gate-switching mechanisms.
