Phase transitions in four-dimensional AdS black holes with a nonlinear electrodynamics source

Ramón Bécar,P A González,Joel Saavedra,Yerko Vásquez,Bin Wang

Figure 5. Gibbs free energy for nonlinear Maxwell electrodynamics for $p=\tfrac{3}{4}$, k = 1, q = 2 and η = 1 in the canonical ensemble. We can see that for P < PC (PC is represented by the dashed line) the system is undergoing a first-order phase transition described by the characteristic swallow tail.