  We have investigated the turbulent mean-field dynamo action in protoneutron
stars that are subject to convective and neutron finger instabilities. While
the first one develops mostly in the inner regions of the star, the second one
is favoured in the outer regions, where the Rossby number is much smaller and a
mean-field dynamo action is more efficient. By solving the mean-field induction
equation we have computed the critical spin period below which no dynamo action
is possible and found it to be ~1 s for a wide range of stellar models. Because
this critical period is substantially longer than the characteristic spin
period of very young pulsars, we expect that a mean-field dynamo will be
effective for most protoneutron stars.
