Geometrothermodynamics of black holes with a nonlinear source

We study thermodynamics and geometrothermodynamics of a particular black hole configuration with nonlinear source. use the mass as fundamental equation, from which it follows that curvature radius must be considered thermodynamic variable, leading to an extended equilibrium space. Using formalism geometrothermodynamics, we show geometric properties space can used obtain information about interaction, critical points phase transitions. these results are compatible obtained classical thermodynamics.