  Telegraph noise caused by frequent switching of the magnetization in small
magnetic devices has become a useful resource for probabilistic computing.
Conventional theories have been based on a linearization of the fluctuations at
the extrema of the magnetic free energy. We show theoretically that the
non-linearities, specifically four-magnon scatterings, reduce the equilibrium
fluctuation amplitude of the magnetization as well as the switching frequencies
between local minima via the decay of the homogeneous Kittel mode into two spin
waves with opposite momenta. Selectively suppressing the effective temperature
of the finite-k spin waves, or reducing the radius of a thin magnetic disk
enhance the switching frequency and improve performance of magnetic tunnel
junctions in probabilistic computing applications.
