Spontaneous magnon decay in altermagnetic Heisenberg spin models at zero temperature

We investigate spontaneous magnon decay in altermagnetic Heisenberg spin models at zero temperature using spin-wave theory. Altermagnets are a recently discovered class of magnets which are characterized by features like time-reversal symmetry breaking and spin-splitting of electronic bands. Using non-linear spin wave theory we can show analytically that there is spontaneous magnon decay. Furthermore, we investigate the momentum dependence of the magnon lifetime.