Reversibly Switchable Electromagnetic Device with Leakage‐Free Electrolyte

Abstract

A reversibly switchable electromagnetic oxide device is demonstrated by using a thin-film transistor structure with a newly developed "leakage-free electrolyte" as a gate insulator. The electrical and magnetic behavior of the device can be switched from antiferromagnetic insulation to ferromagnetic metal electrically under DC voltage of ±3 V at room temperature.The result provides a novel design concept for practical memory device.

Fabrication, Characterization, and Modulation of Functional Nanolayers

“…The percolation AC conductivity is ∼10 −9 S cm −1 , which is comparable to that of ultrapure water. Changing the valence of the transition metal ion by a gate voltage application changes the functional oxide from an insulator to a metal as well as from a nonmagnetic to a magnetic material or from colorless and transparent to a black color is formed in 3 s. On the contrary, a positive gate voltage (+3 V) application to the gate-source electrodes reduces SrCoO 3 into SrCoO 2.5 in 3 s [67]. Figure 10.18a shows a schematic of the device structure, which is similar to conventional three-terminal thin-film transistors.…”

“…The authors have developed two multi-information memory devices, which use a magnetic [67] or optical [68] signal along with an electronic signal to double the storage capacity in these "multiplex writing/reading" devices. In addition to the binary 0/1 method of storing information in a state-of-the-art memory device, the present devices can also store A/B for the information.…”

“…Metal Conversion in SrCoO 2.5+δ [67] To realize "multiplex writing/reading" devices, material selection is the most information factor. Katase and Ohta et al choose strontium cobaltite, SrCoO 2.5+δ , for this purpose because SrCoO 2.5 is an antiferromagnetic insulator and SrCoO 3 is a ferromagnetic metal [69,70].…”

Transition-metal-oxide based functional thin-film device using leakage-free electrolyte

“…Electro-magnetic phase switching device 27) SrCoO x (SCO x ) is classically known to show different electromagnetic properties depending on the oxygen composition (x), which can be varied in the range of 2.53.0, with keeping the crystallographic lattice structure. 15), 49) The most stable phase of SCO 2.5 possesses an oxygen-vacancy ordered brownmillerite (BM-) structure.…”

Macroscopic Visualization of Fast Electrochemical Reaction of SrCoOx Oxygen Sponge

“…SrCoO 2.5 + 0.5O 2− → SrCoO 3 + e − The fully oxidized SrCoO 3 showed metallic electron conduction and ferromagnetic behaviour below room temperature. And the proposed electrochemical memory device showed fast (~2 -3 s) redox reaction under applying relatively low voltage of ±3 V. [9] In order to further improve the device characteristics and to develop practical devices, the electrochemical oxidation needs to be visualized macroscopically. Usually transmission electron microscopy (TEM) observation is powerful tool to visualize the electrochemical redox reaction of a material.…”