Spatially Controlled Octahedral Rotations and Metal-Insulator Transitions in Nickelate Superlattices.
basic_science · Level V
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- Record sourced from PubMed, PMID 33470113.
- Also identified by DOI 10.1021/acs.nanolett.0c03850 and PMC identifier 7883389.
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Abstract
The properties of correlated oxides can be manipulated by forming short-period superlattices since the layer thicknesses are comparable with the typical length scales of the involved correlations and interface effects. Herein, we studied the metal-insulator transitions (MITs) in tetragonal NdNiO<sub>3</sub>/SrTiO<sub>3</sub> superlattices by controlling the NdNiO<sub>3</sub> layer thickness, <i>n</i> in the unit cell, spanning the length scale of the interfacial octahedral coupling. Scanning transmission electron microscopy reveals a crossover from a modulated octahedral superstructure at <i>n</i> = 8 to a uniform nontilt pattern at <i>n</i> = 4, accompanied by a drastically weakened insulating ground state. Upon further reducing <i>n</i> the predominant dimensionality effect continuously raises the MIT temperature, while leaving the antiferromagnetic transition temperature unaltered down to <i>n</i> = 2. Remarkably, the MIT can be enhanced by imposing a sufficiently large strain even with strongly suppressed octahedral rotations. Our results demonstrate the relevance for the control of oxide functionalities at reduced dimensions.