[18p-E311-1~18] 6.3 Oxide electronics

△ [18p-E311-3] Observation of Current-Dependent Metal-Insulator Transition in Ca₂RuO₄ Thin Films Grown by Solid Phase Epitaxy

〇Keiji Tsubaki¹, Atsushi Tsurumaki-Fukuchi¹, Takayoshi Katase², Toshio Kamiya², Masashi Arita¹, Yasuo Takahashi¹ (1.Graduate School of IST, Hokkaido Univ., 2.MSL, Tokyo Tech.)

Keywords:metal-insulator transition, ruthenium oxide, solid phase epitaxy

For narrow-gap Mott insulator Ca₂RuO₄, recent works have suggested the possibility of electric-stimuli-based induction of the metal-insulator transition, such as applications of currents and voltages. The electrically-driven transition of Ca₂RuO₄ has attracted much recent attentions owing to the rich electronic properties of the induced metallic phase and potential for device applications. In Ca₂RuO₄, however, the high volatility of Ru is known to make the fabrication of epitaxial thin films of Ca₂RuO₄ especially difficult. The metal-insulator transition has not been observed in the thin films of Ca₂RuO₄, which are critically important both for the mechanism understanding and device developments, because of the easy formation of Ru deficiencies. In this study we tried to develop high-quality thin films of Ca₂RuO₄ based on solid state epitaxy where atmospheric pressure film growth and resultant reduction of Ru evaporation is possible, and explored the possibility of electrical induction of the metal-insulator transition. As the results, we observed a unique metal-insulator transition in the developed thin films of Ca₂RuO₄, where the resistivity and transition temperature is strongly dependent on the applied currents and voltages. The electrical sensitivity of the transition and emergent electronic properties of Ca₂RuO₄ was successfully demonstrated in the thin films.