Quantum pumping in helimagnet heterostructures

Abstract

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.