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Cationic Redistribution at Epitaxial Interfaces in Superconducting Two-Dimensionally Doped Lanthanum Cuprate Films
journal contribution
posted on 2016-09-20, 00:00 authored by Federico Baiutti, Giuliano Gregori, Yi Wang, Y. Eren Suyolcu, Georg Cristiani, Peter
A. van Aken, Joachim Maier, Gennady LogvenovThe
exploration of interface effects in complex oxide heterostructures
has led to the discovery of novel intriguing phenomena in recent years
and has opened the path toward the precise tuning of material properties
at the nanoscale. One recent example is space-charge superconductivity.
Among the complex range of effects which may arise from phase interaction,
a crucial role is played by cationic intermixing, which defines the
final chemical composition of the interface. In this work, we performed
a systematic study on the local cationic redistribution of two-dimensionally
doped lanthanum cuprate films grown by oxide molecular beam epitaxy,
in which single LaO layers in the epitaxial crystal structure were
substituted by layers of differently sized and charged dopants (Ca,
Sr, Ba, and Dy). In such a model system, in which the dopant undergoes
an asymmetric redistribution across the interface, the evolution of
the cationic concentration profile can be effectively tracked by means
of atomically resolved imaging and spectroscopic methods. This allowed
for the investigation of the impact of the dopant chemistry (ionic
size and charge) and of the growth conditions (temperature) on the
final superconducting and structural properties. A qualitative model
for interface cationic intermixing, based on thermodynamic considerations,
is proposed. This work highlights the key role which cationic redistribution
may have in the definition of the final interface properties and represents
a further step forward the realization of heterostructures with improved
quality.