Electronic response of a Mott insulator at a current-induced insulator-to-metal transition

The Mott insulator Ca₂RuO₄ exhibits an insulator-to-metal transition induced by d.c. current. Despite the thorough examination of the structural changes associated with this transition, a comprehensive knowledge of the response of electronic degrees of freedom is still lacking. Here we demonstrate current-induced modifications of the electronic states of Ca₂RuO₄. Angle-resolved photoemission spectroscopy in conjunction with four-probe electrical transport (transport-ARPES) measurements reveal a clear reduction of the Mott gap and a modification in the dispersion of the Ru bands. Based on a free-energy analysis, we show that the current-induced phase is electronically distinct from the high-temperature zero-current metallic phase. Our results highlight strong interplay of lattice- and orbital-dependent electronic responses in the current-driven insulator-to-metal transition.

C. T. Suen, I. Marković, M. Zonno, N. Heinsdorf, S. Zhdanovich, N. H. Jo, M. Schmid, P. Hansmann, P. Puphal, K. Fürsich, S. Smit, C. Au-Yeung, V. Zimmermann, B. Zwartsenberg, M. Krautloher, I. S. Elfimov, R. Koch, S. Gorovikov, C. Jozwiak, A. Bostwick, M. Franz, Eli Rotenberg, B. Keimer, A. Damascelli