  Altermagnetism is a subclass of antiferromagnetism that features
spin-polarized electron bands of a non-relativistic origin despite the absence
of a net magnetiation in the material. We here theoretically study spin pumping
from an altermagnetic insulator into a normal metal. The symmetry properties of
the lattice and spin order of the altermagnet alters the magnon dispersion
compared to a conventional square lattice antiferromagnet. Nevertheless, the
pumped spin current turns out to be equal to the current which is pumped from a
conventional antiferromagnet. This occurs so long that the magnetic field which
sets the altermagnetic spins into precessional motion is spatially homogeneous.
These results show that while spin pumping is possible using altermagnets, the
altermagnetic spin order does not readily leave unique fingerprints in the
pumped spin current. Our model provides a suitable starting point for
investigating more complex models where finite momentum magnons contribute to
spin pumping due to magnon-magnon interactions or where the magnetic field
inducing spin pumping is spatially inhomogeneous.

Mesoscale and Nanoscale Physics