Electric-Field-Induced Superconductivity on an Organic/Oxide Interface

Abstract

Many superconductors have been developed by inducing charge carriers into a mother insulator compound. Chemical substitution of impurity atoms is usually used for inducing charge carriers, and this method is called “chemical doping”. Another method to tune charge carrier density is the electric field effect, which is widely utilized as a field-effect transistor. Here, we review recent progress in an electric field-effect study for developing a new oxide superconductor with an organic electrolyte gate. We first present a device configuration of an electric double layer transistor with oxide semiconductors, SrTiO3 and KTaO3. We then present the electrochemical interface properties and room-temperature device characteristics with various electrolytes. Finally, we present the superconductivity emerging at an organic/oxide interface, and discuss the phase diagram of electric-field-induced superconductors by comparing with superconductors obtained by chemical doping.

Dual field effects in electrolyte-gated spinel ferrite: electrostatic carrier doping and redox reactions

“…In particular, the field effect with ionic liquid electrolytes demonstrating field-induced superconductivity 2 3 and carrier-induced ferromagnetism 4 in insulators, in addition to electronic phase switching in strongly electron correlated systems 5 6 7 8 9 10 11 12 13 14 , has furthered this field. This method is characterized by an ultrathin capacitor-like structure formed by electrolyte ions at the electrolyte/oxide interface, called the electric double layer (EDL) 15 . The very strong electric field generated within the EDL makes it possible to accumulate a high density of charge carriers on the oxide channel (as high as 10 14–15 cm −2 ), without being restricted by the hetero-structuring processes generally required for experiments with solid gate dielectrics.…”