A field effect control of a metal–insulator transition in strongly correlated electron systems has been one of the main topics in material science in the past decades. In this context, the electric double-layer transistor (EDLT), an ionic liquid-gated FET, plays an important role in terms of how the extremely-high electric fields can be applied for the gate control of electronic phases. In this talk, the tuning of electronic properties in EDLT devices on strongly correlated oxides will be discussed.

A Half-doped manganite of Pr0.5Sr0.5MnO3 exhibits the strong competition between a ferromagnetic-metallic and an antiferromagnetic-insulating phases1. The simultaneous application of gate voltage and a magnetic field to this system leads to a peculiar response in the resistance. Indeed, the gigantic resistance switching with a mere 50 mV tweaking of gate voltage was achieved2. On the other hand, a gate control of metal-insulator transition at room temperatures has been clearly realized in VO2-based FET. These results pave a way towards the realization of Mott-transistors4: a concept of phase-transition based FET, which may solve the scaling limit and the power-consumption issue. Although the electrostatic carrier doping is a key to realize above results, the utilization of the chemical reaction induced at the interface between the ionic liquid and the channel materials would be also possible by choosing the proper materials. The recent work for this topic, done on iron oxides based devices, will be also discussed.

This research was supported by the Japan Society for the Promotion of Science (JSPS) through its “Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST Program)”, initiated by the Council for Science and Technology Policy (CSTP), and Grant-in-Aid for Young Scientists Grant (No. 26790052).