Rational non-linear electrodynamics of AdS black holes and extended phase space thermodynamics

Abstract

The critical behaviour of magnetically charged AdS black holes based on rational non-linear electrodynamics (RNED) in an extended phase space is investigated herein. The cosmological constant is considered as thermodynamic pressure, and the black hole mass is identified with the chemical enthalpy. An analogy with the van der Walls liquid–gas system is found, and the critical exponents coincide with those of the van der Waals system. The thermodynamics of RNED-AdS black holes and phase transitions are studied, and new thermodynamic quantities conjugated to the non-linear parameter of RNED and magnetic charge are defined. The consistency of the first law of black hole thermodynamics and the Smarr formula is demonstrated.