  In a recent letter Alonso et al. (Phys. Rev. Lett. 87, 097205 (2001)) present
Monte Carlo simulations for interacting dipoles. Short-time relaxation was
caused by a simple noise field, acting uniformly over an "energy window" of
small width (to simulate the fluctuating nuclear spin bias). However, the
physics of the tunneling relaxation of an ensemble of tunneling nanomagnets or
magnetic molecules (as well as of the "tunneling hole" formation) is different
and here we discuss this point.
