  I consider a single-level quantum dot coupled to two reservoirs of spin waves
(magnons). Such systems have been studied recently from the point of view of
possible coupling between electronic and magnonic spin currents. However,
usually weakly coupled systems were investigated. When coupling between the dot
and reservoirs is not weak, then higher order processes play a role and have to
be included. Here I consider cotunneling of magnons through a spin-occupied
quantum dot, which can be understood as a magnon (spin) leakage current in
analogy to leakage currents in charge-based electronics. Particular emphasis
has been put on investigating the effect of magnetic field and temperature
difference between the magnonic reservoirs.
