Ionic Liquid Gate-Induced Modifications of Step Edges at SrCoO_2.5 Surfaces

Area of Science:

• Materials Science
• Surface Science
• Electrochemistry

Background:

• Intense electric fields at ionic liquid-oxide interfaces induce phase transitions in oxides.
• Ionic liquid gating reversibly transforms brownmillerite SrCoO_2.5 to perovskite SrCoO₃.

Purpose of the Study:

• To investigate the surface modifications of SrCoO_2.5 films under ionic liquid gating.
• To understand the mechanisms behind these surface changes and their implications for ionitronics.

Main Methods:

• In situ atomic force microscopy with photothermal excitation detection for high-quality measurements in ionic liquids.
• X-ray photoemission spectroscopy to analyze surface composition.

Main Results:

• Ionic liquid gating significantly modifies the edges of SrCoO_2.5 terraces.
• Terraces remain atomically smooth, but their edges develop distinct ridges.
• These ridges are formed by the adsorption of hydroxyl groups.

Conclusions:

• Electrical control via ionic liquid gating can induce specific surface modifications on oxide films.
• Hydroxyl adsorption at film edges is a key mechanism for electrically controlled surface restructuring.
• Findings pave the way for novel ionitronic applications leveraging surface engineering.