Emergent Device Research Team

Principal Investigator

PI Name Yoshihiro Iwasa
Degree Ph. D.
Title Team Leader
Brief Resume
1986Ph. D., University of Tokyo
1986Research Associate, Department of Applied Physics, University of Tokyo
1991Lecturer, Department of Applied Physics, University of Tokyo
1994Associate Professor, School of Materials Science, Japan Advanced Institute of Science and Technology
2001Professor, Institute for Materials Research, Tohoku University
2010Professor, Quantum-Phase Electronics Center, University of Tokyo (-present)
2010Team Leader, Strong-Correlation Hybrid Materials Research Team, RIKEN
2013Team Leader, Emergent Device Research Team, Supramolecular Chemistry Division, RIKEN Center for Emergent Matter Science (-present)


The purpose of Emergent Device Research Team is to discover novel quantum functionalities and create revolutionary energy materials based on the concept of iontronics, ion controlled electronics. Specifically, control of quantum phase transitions and optimization of functionality are made by a wide range of carrier density tuning using electric double layer transistors of two-dimensional (2D) materials, nanotubes, and quantum dots of various oxides and chalcogenides. Such a unique combination of nanomaterials and iontronics concept enables us to realize 2D superconductivity, phase transitions of strongly correlated electron systems, control of valley or spin currents, and developments of new thermoelectric materials.

Research Fields

Physics, Engineering, Chemistry, Materials Sciences


Electric double layer transistor
2D materials
Thermoelectric effect


Iontronics toward Revolutionary Energy Materials

  We are proposing a new concept “iontronics”, which means electronics controlled by motions and arrangements of ions. By introducing Iontronics, we are nowadays able to go beyond the conventional current switching devices and to realize voltage-controlled electronic phase transitions, including superconductivity, ferromagnetism, and metal-insulator transitions. Iontronics is growing up to an interdisciplinary field stemming from electrochemistry, materials science, condensed matter physics to energy materials.

A representative device iontronics is an electric double layer transistor (EDLT), which enables the high density carrier accumulation at the electrolyte-solid interfaces. Left figure shows the temperature-dependence of resistance of vanadium dioxide (VO2), demonstrating the field-induced insulator-metal transition with only 1 V. Right figure depicts the optimization of the thermoelectric power factor in zinc oxide (ZnO), an archetypal oxide semiconductor, as a function of carrier density, demonstrating a comparable power factor to that of the practically used Bi2Te3. These achievements are indicating novel routes toward the next generation low power consumption devices as well as revolutionary energy materials.

Left: Gate-induced esistance switching in VO2 EDLT.
Adapted from “Nature 487, 459-462 (2012).” with permission (© 2012 Nature)
Right: Optimization of thermoelectric power factor of ZnO with EDLT.
Adapted from “PNAS, 113, 6438-6443 (2016).” with permission


Yoshihiro Iwasa

Team Leader iwasay[at]riken.jp R

Satria Bisri

Research Scientist satria.bisri[at]riken.jp R

Masaro Yoshida

Postdoctoral Researcher



2-1 Hirosawa, Wako, Saitama 351-0198 Japan