66th CEMS Colloquium

Title

Non-Equilibrium Steady States (NESS): a powerful approach to control Mott insulators

Abstract

DC current can be a powerful tuning parameter of the electronic states of strongly correlated electron systems in the vicinity of Mott transitions. In this presentation, we give a short review on the research progress on the novel phenomena in the layered perovskite Ca₂RuO₄ and related materials.

Under DC current, Ca₂RuO₄ with a small Mott gap (~ 0.4 eV) exhibits semimetallic transport behavior with giant diamagnetism at low temperatures [1]. We attribute this behavior to emergent “Mott semimetal” state, in which the upper and lower Hubbard bands become tiny electron and hole pockets with light quasiparticle mass responsible for the large diamagnetism.

It demonstrate that in a non-equilibrium steady state (NESS) introduced by DC current, a Mott insulator with a small gap can be readily driven into novel electronic states.

This work is done mainly in collaboration with C. Sow, R. Numasaki, S. Yonezawa, F. Nakamura, T. Oka, S. Kitamura, K. Kuroki, D. Shibata, T. Yoshida, and N. Kikugawa. This work was supported by JSPS KAKENHI Nos. JP15H05852, and JP15K21717.

[1] C. Sow, S. Yonezawa, S. Kitamura, T. Oka, K. Kuroki, F. Nakamura, Y. Maeno, Science 358, 1084 (2017)