PHASE TRANSITION, GEOMETROTHERMODYNAMICS AND CRITICAL EXPONENTS OF BARDEEN BLACK HOLE

In this paper, we investigate the phase transition of Bardeen black hole for the first time. First, we calculate thermodynamic quantities and correct the misuse of formula in former literature. Second, we investigate in detail the behavior of specific heat. We not only discuss the influence of parameter on phase transition, but also show the three-dimensional behavior of the specific heat. It is shown that phase transition takes place from a locally unstable large black hole to a locally stable small black hole. It is also shown that the location of phase transition point is proportional to the charge. Meanwhile, we study the behavior of the inverse of the isothermal compressibility and find that it diverges at the phase transition point. Thirdly, we build up geometrothermodynamics to examine the phase transition structure. It is shown that Legendre invariant thermodynamic scalar curvature diverges exactly where the specific heat diverges, which leads to the conclusion that the Legendre invariant metrics can correctly produce the behavior of the phase transition structure. Furthermore, to gain a thorough understanding of critical behavior, we calculate the relevant critical exponents and examine the scaling laws. It is shown that they are in agreement with the scaling laws.