Reversible phase transformation and comprehensive phase diagram in SrCoO2.5+x(0≤x≤0.5) with the electric field control of oxygen content

Abstract

Oxygen deficiency plays an essential role in tailoring the intriguing physical properties of complex oxides that can be harnessed in the cutting-edge energy and information technologies. A fine and continuous control of the oxygen content to modulate the rich physical properties of the complex oxides is highly desirable for both basic research and modern electronic technologies. Here, we report a recently developed ionic field-effect transistor (iFET) device with a solid oxygen ionic conductor (OIC) as the gate dielectric to finely and continuously control the oxygen content of the oxides. We realize a reversible structural transformation between brownmillerite $\mathrm{SrCo}{\mathrm{O}}_{2.5}$ and perovskite $\mathrm{SrCo}{\mathrm{O}}_{3}$ by driving oxygen ions in and out of the samples with the OICFET at room temperature. With continuously changing the oxygen content, a comprehensive phase diagram of the $\mathrm{SrCo}{\mathrm{O}}_{2.5+x}$ $(0\ensuremath{\le}x\ensuremath{\le}0.5)$ thin film from an antiferromagnetic insulator to a ferromagnetic metal is obtained in a single device. Our work provides a promising route to continuously and reversibly regulate the oxygen content and to explore unique physical states in the correlated electron oxides, and represents an important step towards the realization of a long-standing goal to develop complex oxide based devices that can be integrated with existing technologies.