  We used Raman light scattering to study the current-stabilized nonequilibrium
semimetallic and metallic phases in Ca$_2$RuO$_4$. By determining the local
temperature through careful analysis of the Stokes and anti-Stokes intensities,
we find that Joule heating can be completely avoided by supplying sufficient
cooling power in a helium-flow cryostat, and that the current induces the
semimetallic state without inducing any significant heating. We further
investigate the current-induced semimetallic state as a function of temperature
and current. We confirm the absence of long-range antiferromagnetic order and
identify a substantial Fano broadening of several phonons, which suggests
coupling to charge and orbital fluctuations. Our results demonstrate that the
semimetallic state is a genuine effect of the applied electrical current and
that the current-induced phases have characteristics distinct from the
equilibrium ones.
