  We study the magnetic phase diagram of an ensemble of dipolar hard spheres
(DHS) with or without uniaxial anisotropy and frozen in position on a
disordered structure by tempered Monte Carlo simulations. The crucial point is
to consider an anisotropic structure, obtained from the liquid state of the
dipolar hard spheres fluid, frozen in its polarized state at low temperature.
The freezing inverse temperature $\beta_f$ determines the degree of anisotropy
of the structure which is quantified through a structural nematic order
parameter, $\lambda_s$. The case of the non zero uniaxial anisotropy is
considered only in its infinitely strong strength limit where the system
transforms in a dipolar Ising model (DIM). The important finding of this work
is that both the DHS and the DIM with a frozen structure build in this way
present a ferromagnetic phase at volume fractions below the threshold value
where the corresponding isotropic DHS systems exhibit a spin glass phase at low
temperature.
