Magnetic catalysis in three-dimensional QED at finite temperature: Beyond the constant mass approximation

We solve the Schwinger-Dyson equations for (2+1)-dimensional QED in the presence of a strong external magnetic field. The calculation is done at finite temperature and the fermionic self-energy is not supposed to be momentum independent, which is the usual simplification in such calculations. The phase diagram in the temperature-magnetic field plane is determined. For each value of the magnetic field the critical temperature is higher than in the constant mass approximation. In addition, the latter approximation shows a relative B independence of the critical temperature, which occurs for stronger magnetic fields in the momentum dependent case.