Control of the electronic states of Ca2RuO4 by uniaxial pressure

We study the uniaxial pressure effect on the Mott insulator Ca2RuO4. It is known that the crystal structure is a crucial parameter to determine the electronic states in this system. We revealed that a metal-insulator (M-I) transition is induced by the uniaxial pressure along the ab-plane at room temperature and the metallic state is sustained under cooling down to 5 K. In contrast, such a transition to a metallic state is not observed by the uniaxial pressure along the c-axis. Our experimental results suggest that the elongation of the RuO6 octahedra along the c-axis can trigger the M-I transition.