Atomic-Scale Metal-Insulator Transition in SrRuO<sub>3</sub> Ultrathin Films Triggered by Surface Termination Conversion.
basic_science · Level V
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- Record sourced from PubMed, PMID 31830343.
- Also identified by DOI 10.1002/adma.201905815.
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Abstract
The metal-insulator transition (MIT) in transition-metal-oxide is fertile ground for exploring intriguing physics and potential device applications. Here, an atomic-scale MIT triggered by surface termination conversion in SrRuO<sub>3</sub> ultrathin films is reported. Uniform and effective termination engineering at the SrRuO<sub>3</sub> (001) surface can be realized via a self-limiting water-leaching process. As the surface termination converts from SrO to RuO<sub>2</sub> , a highly insulating and nonferromagnetic phase emerges within the topmost SrRuO<sub>3</sub> monolayer. Such a spatially confined MIT is corroborated by systematic characterizations on electrical transport, magnetism, and scanning tunneling spectroscopy. Density functional theory calculations and X-ray linear dichroism further suggest that the surface termination conversion breaks the local octahedral symmetry of the crystal field. The resultant modulation in 4d orbital occupancy stabilizes a nonferromagnetic insulating surface state. This work introduces a new paradigm to stimulate and tune exotic functionalities of oxide heterostructures with atomic precision.