  The finite temperature phase diagram of a U(1) Higgs-Yukawa model at a finite
value of the scalar self coupling $\lambda$ is investigated by means of a
large-$N_f$ calculation and numerical simulations. The phase diagram is similar
to the one at zero temperature and shows a ferromagnetic, two symmetric and an
antiferromagnetic phase. However, the phase transition lines are shifted to
larger values of the Yukawa coupling demonstrating the occurence of the finite
temperature symmetry restoration.
