Numerical evidence for unstable magnons at high fields in the square lattice Heisenberg antiferromagnet

We have found numerical evidence for decaying magnons in the square lattice spin-1/2 Heisenberg antiferromagnet when it is exposed to a strong external magnetic field. The results are obtained using Quantum Monte Carlo simulations combined with a Bayesian inference technique to obtain dynamics, and are consistent with earlier predictions from spin wave theory.