Raman scattering from current-stabilized nonequilibrium phases in Ca₂RuO₄

We used Raman light scattering to study the current-stabilized nonequilibrium semimetallic and metallic
phases in Ca₂RuO₄. 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 [1]. We further investigate the current-induced semimetallic state as a function of temperature and current.
We confirm the absence of long-range antiferromagnetic order [2] 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.
[1] K. Fürsich et al., Phys. Rev. B 100, 081101(R) (2019)
[2] J. Bertinshaw et al., Phys. Rev. Lett. 123, 137204 (2019)