Electric Polarization Switching on an Atomically Thin Metallic Oxide.

Ye, Mao; Hu, Songbai; Zhu, Yuanmin; Zhang, Yubo; Ke, Shanming; Xie, Lin; Zhang, Yuan; Hu, Sixia et al. · Nano Lett · 2021

basic_science · Level V

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Abstract

Materials with reduced dimensions have been shown to host a wide variety of exotic properties and novel quantum states that often defy textbook wisdom. Polarization switching and metallic screening are well-known examples of mutually exclusive properties that cannot coexist in bulk solids. Here we report the fabrication of (SrRuO<sub>3</sub>)<sub>1</sub>/(BaTiO<sub>3</sub>)<sub>10</sub> superlattices that exhibits reversible polarization switching in an atomically thin metallic layer. A multipronged investigation combining structural analyses, electrical measurements, and first-principles electronic structure calculations unravels the coexistence of two-dimensional (2D) metallicity in the SrRuO<sub>3</sub> layer accompanied by the breaking of inversion symmetry, supporting electric polarization along the out-of-plane direction. Such a 2D ferroelectric-like metal paves a novel way to engineer a quantum multistate with unusual coexisting properties, such as ferroelectrics and metals, manipulated by external fields.