Geometrothermodynamics of a charged black hole of string theory

The thermodynamics of the Gibbons-Maeda-Garfinkle-Horowitz-Strominger charged black hole from string theory is reformulated within the context of the recently developed formalism of geometrothermodynamics. The geometry of the space of equilibrium states is curved, but we show that the thermodynamic curvature does not diverge at the phase transition point expected when the black hole solution becomes a naked singularity. This provides a counterexample to the conventional notion that such a divergence signals the occurrence of a second-order phase transition. (author)