  The magnetic properties of RMn2O5 multiferrroics as obtained by unpolarized
and polarized neutron diffraction experiments are reviewed. We discuss the
qualitative features of the magnetic phase diagram both in zero magnetic field
and in field and analyze the commensurate magnetic structure and its coupling
to an applied electric field. The origin of ferrolectricity is discussed based
on calculations of the ferroelectric polarization predicted by different
microscopic coupling mechanisms (exchange striction and cycloidal spin-orbit
models). A minimal model containing a small set of parameters is also presented
in order to understand the propagation of the magnetic structure along the
c-direction.
