Strongly-correlated quantum materials exhibit a variety of exotic phenomena as represented by high-temperature superconductivity, colossal magnetoresistance, and metal-insulator transitions, originating from strong couplings among multiple degrees of freedom including charge, orbital, spin, and lattice. In this study, we focus on transition-metal compounds and their integrated superstructures, where correlated d-electrons play an essential role. We apply ion-gating technique to those correlated quantum materials to realize gate-induced phase transitions, and explore novel quantum phases associated with the cooperative phenomena among correlated electrons in those systems.

Van der Waals (vdW) superstructures made of different types of 2D materials such as graphene and MoS2 enable design and creation of various properties and functionalities that are missing in their bulk counterparts and individual 2D materials. In this study, we focus on 2D quantum materials having a variety of quantum phases as their ground states. We construct vdW superstructures based on those materials by molecular-beam epitaxy (MBE), and explore novel quantum phases associated with the symmetry breaking as well as the strong proximity effect at those vdW interfaces.