  Boltzmann's microcanonical entropy is the link between statistical physics
and thermodynamics, forasmuch as the behavior of any thermodynamic quantity is
directly related to the number of microscopic configurations. Accordingly, in
this work, we investigate the behavior of the logarithm of the density of
states of the three-state Potts model with an external field applied to one of
the states using joint entropic simulations based on the Wang-Landau algorithm.
Our analysis reveals that the microcanonical entropy curve is detachable, and
each resulting path is related to the formation of clusters. Such a description
is consistent with the energy-entropy argument related to the inception of a
phase transition. When the external field is reversed and strong, the observed
phase transition is from an ordered configuration to cluster formations. The
behavior of the microcanonical inverse temperature indicates both first and
second-order phase transitions occurring at different temperatures for high
values of the external field.
