  In condensed matter physics, chirality of elementary particles and
quasiparticles plays an important role in many unconventional phenomena such as
the quantum Hall effect and the chiral phonon excitations . In magnetic
materials, magnons are chiral quasiparticles to characterize the quantized spin
excitations. However, chiral phenomena of magnons have been barely studied
because magnons in ferromagnets (FM) carry right-handed chirality only.
Although antiferromagnets (AFM) support both right-handed and left-handed
chiralities of magnons , , chiral phenomena induced by AFM magnons remain
unspecified to date because of the complex in spin dynamics , and the obstacles
of THz broadband magnetic excitations , . On the contrary, ferrimagnets, which
combine the characteristics of FM and AFM, offer a new opportunity for the
exploration of chiral phenomena in GHz frequency range , . Here we report
chiral spin pumping in artificial ferrimagnet of Py/Gd/Py/Gd/Py/Pt multilayers.
We realized both right-handed and left-handed chiralities of the Py
magnetization precessions at high and low temperature, respectively, and
demonstrate unambiguously that opposite chiralities of Py precession pump
opposite spin polarizations of the spin current into the Pt layer. Our result
promises new functionalities and computing architectures in spintronics based
on the chirality of magnons.
