Spatially Controlled Octahedral Rotations and Metal-Insulator Transitions in Nickelate Superlattices.
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 NdNiO3/SrTiO3 superlattices by controlling the NdNiO3 layer thickness, n 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 n = 8 to a uniform nontilt pattern at n = 4, accompanied by a drastically weakened insulating ground state. Upon further reducing n the predominant dimensionality effect continuously raises the MIT temperature, while leaving the antiferromagnetic transition temperature unaltered down to n = 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.
['Chen|Binbin|B|', 'Gauquelin|Nicolas|N|', 'Green|Robert J|RJ|', 'Lee|Jin Hong|JH|http://orcid.org/0000-0002-1423-1438', 'Piamonteze|Cinthia|C|http://orcid.org/0000-0002-8416-9668', 'Spreitzer|Matjaž|M|', 'Jannis|Daen|D|', 'Verbeeck|Johan|J|', 'Bibes|Manuel|M|http://orcid.org/0000-0002-6704-3422', 'Huijben|Mark|M|http://orcid.org/0000-0001-8175-6958', 'Rijnders|Guus|G|', 'Koster|Gertjan|G|http://orcid.org/0000-0001-5478-7329']
nickelate superlattice dimensionality strain metal−insulator transition oxygen octahedral rotations