Iwasa Yoshihiro (SIMES Seminar)

Date(s) - Apr 10 2015
11:00 AM - 12:00 PM

Shasta Room, Bldg. 40, Room 361


Emergent Iontronics

Yoshi Iwasa

Quantum-Phase Electronics Center & Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan

RIKEN Center for Emergent Matter Science, Wako 351-0198, Japan


In your mobile phones, there are two kinds of important devices, billions of transistors and a battery. The transistor controls electron flow in a semiconductor to enable processing and storage of information, while the latter stores electrochemical energy for driving the former. In the latest decade, devices with combined concepts of transistors and batteries, electrochemical transistors, are receiving increasing interests, because they can offer new opportunities beyond conventional current switching functions of all solid transistors.

Surprises came from a simple replacement of solid gate dielectrics in field effect transistors (FETs) with electrolytes, which allow us to form two dimensional (2D) electron systems at the transistor channel with the density of 1014 cm-2, which is 1 – 2 orders of magnitude larger than that achieved in conventional FETs. This type of electrochemical transistor was named as electric double layer transistor (EDLT). Taking advantage of ultrahigh density 2D electron systems, we have successfully realized electric field induced superconductivity [1], ferromagnetism [2], Mott-Hubbard transition [3], which have been impossible or at least extremely difficult in conventional all solid FETs.

In particular, the 2D crystals from transition metal dichalcogenides and other layered materials offer an ideal platform for the EDLT device, due to their dangling bond free surface structures. In fact, we have demonstrated electric field induced superconductivity [4] and chiral light source [5] based on EDLTs of 2D crystals. EDLT is creating an innovative concept of field effect phase control in a variety of materials. In this lecture, I will review the current status of “Emergent Iontronics”, electronics based on ionic functions [6].



[1] K. Ueno et al., Nat. Mater. 7, 855 (2008).

[2] Y. Yamada et al., Science 127, 1065 (2011).

[3] M. Nakano et al., Nature 487, 459 (2012).

[4] J. T. Ye et al., Science 338, 1193 (2012).

[5] Y. J. Zhang et al., Science 344, 725 (2014).

[6] M. Kawasaki and Y. Iwasa, Nature 489, 510 (2012).