The last lost charge and phase transition in Schwarzschild AdS minimally coupled to a cloud of strings

Abstract.

In this paper we study the Schwarzschild AdS black hole with a cloud of string background in an extended phase space and investigate a new phase transition related to the topological charge. By treating the topological charge as a new charge for the black hole solution we study its thermodynamics in this new extended phase space. We treat by two approaches to study the phase transition behavior via both T-S and P-v criticality and we find the results confirm each other in a nice way. It is shown that a cloud of strings affects the critical physical quantities and it could be observed an interesting Van der Waals-like phase transition in the extended thermodynamics. The swallow tail-like behavior is also observed in the free energy-temperature diagram. We observe in the $a\rightarrow 0$ limit that the small/large black hole phase transition reduces to the Hawking-Page phase transition as we expected. We can deduce that the impact of the cloud of strings in the Schwarzschild black hole can bring a Van der Waals-like black hole phase transition.