posted on 2021-01-20, 13:35authored byBinbin Chen, Nicolas Gauquelin, Robert J. Green, Jin Hong Lee, Cinthia Piamonteze, Matjaž Spreitzer, Daen Jannis, Johan Verbeeck, Manuel Bibes, Mark Huijben, Guus Rijnders, Gertjan Koster
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.