Electronic structure changes in Ca₂RuO₄ under DC current as observed with angle-resolved photoemission

The quasi-two-dimensional Mott insulator Ca₂RuO₄ exhibits a convergence of spin-orbit coupling and electron correlations that lead to exciting quantum phenomena, including a rare insulator-to-metal transition induced by a DC current. While structural changes have been tracked in neutron diffraction, Raman scattering, and x-ray studies, associated electronic changes have yet to be observed. We report the first angle-resolved photoemission spectroscopy (ARPES) results that track a change in the dispersion of the ruthenium t_2g bands of a bulk Ca₂RuO₄ crystal in four-probe configuration. These results provide insight into the curious nature of the current-induced transition and advances the difficult technique of conducting photoemission while a current runs through the sample.