Landau-Ginzburg theory of phase transitions in heated rotating nuclei

The Landau-Ginzburg theory is applied to heated rotating superfluid systems. It is demonstrated that the free energy F' is an even function of the order parameter Δ even when external fields are present. The energy surfaces F'(Δ) are calculated for various rotational frequencies and temperatures. These surfaces provide clear illustrations of first-order and second-order phase transitions, as well as a critical point. (orig.)