  We have performed a large scale Monte Carlo simulation of a dilute classical
Heisenberg model with ferromagnetic nearest neighbor and antiferromagnetic
next-nearest neighbor interactions. We found that the model reproduces a
reentrant spin-glass transition. That is, as the temperature is decreased, the
magnetization increases rapidly below a certain temperature, reaches a maximum
value, then ceases at some lower temperature. The low temperature phase was
suggested to be a spin-glass phase that is characterized by ferromagnetic
clusters.
