Triple points and phase transitions of D-dimensional dyonic AdS black holes with quasitopological electromagnetism in Einstein–Gauss–Bonnet gravity

Abstract

By considering the negative cosmological constant Λ as a thermodynamic pressure, we study the thermodynamics and phase transitions of the D-dimensional dyonic AdS black holes (BHs) with quasitopological electromagnetism in Einstein–Gauss–Bonnet (EGB) gravity. The results indicate that the small/large BH phase transition that is similar to the van der Waals (vdW) liquid/gas phase transition always exists for any spacetime dimensions. Interestingly, we then find that this BH system exhibits a more complex phase structure in 6-dimensional case that is missed in other dimensions. Specifically, it shows for D = 6 that we observed the small/intermediate/large BH phase transitions in a specific parameter region with the triple point naturally appeared. Moreover, when the magnetic charge turned off, we still observed the small/intermediate/large BH phase transitions and triple point only in 6-dimensional spacetime, which is consistent with the previous results. However, for the dyonic AdS BHs with quasitopological electromagnetism in Einstein–Born–Infeld (EBI) gravity, the novel phase structure composed of two separate coexistence curves observed by Li et al. [Phys. Rev. D105 104048 (2022)] disappeared in EGB gravity. This implies that this novel phase structure is closely related to gravity theories, and seems to have nothing to do with the effect of quasitopological electromagnetism. In addition, it is also true that the critical exponents calculated near the critical points possess identical values as mean field theory. Finally, we conclude that these findings shall provide some deep insights into the intriguing thermodynamic properties of the dyonic AdS BHs with quasitopological electromagnetism in EGB gravity.