The influence of heating temperature on magnetization reversal process of SrCoO3−δ epitaxial thin film mediated through ionic liquid−gated technology

Abstract

The utilization of ionic liquid gating (ILG) as a gate dielectric to modulate the oxygen (O²⁻) ions of transition metal oxides and thereby control their various properties, holding potential applications in the area of electronics and energy storage. However, numerous experiments have indicated the challenge of fast and reversibly extracting or inserting O²⁻ ions across the entire oxide structure at room temperature (RT). Here, the impact of ILG manipulation on magnetic properties in perovskite SrCoO_3−δ (PV−SCO, 0 < δ < 0.25) epitaxial thin films is explored by varying the heating temperatures. The findings demonstrate that due to the difficulty of inserting O²⁻ ions completely into the entire sample following manipulation with 0 V$\stackrel{30\min }{\to }$+ 4 V$\stackrel{30\min }{\to }$−4 V gate voltages at RT, the magnetic hysteresis (M−H) loop displays a pronounced exchange bias (EB) effect attributed to the coexistence of the PV−SCO ferromagnetic (FM) phase and brownmillerite SrCoO_2.5+x (BM−SCO, 0 < x < 0.25) antiferromagnetic (AFM) phase in the final thin film. Upon increasing the heating temperature to 40 ℃, the BM−SCO and PV−SCO phases undergo rapid and reversible interconversion after stimulating with 0 V$\stackrel{10\min }{\to }$+ 4 V$\stackrel{10\min }{\to }$−4 V gate voltages, and the final thin film reveals a magnetic reversal process of a singular FM phase. Higher heating temperature will instigate irreversible electrochemical reactions between thin film's surface and the ionic liquid, leading to a significant degradation of both the structure and magnetic properties.