Interfacial B-site atomic configuration in polar (111) and non-polar (001) SrIrO3/SrTiO3 heterostructures

Abstract

The precise control of interfacial atomic arrangement in ABO3 perovskite heterostructures is paramount, particularly in cases where the subsequent electronic properties of the material exhibit geometrical preferences along polar crystallographic directions that feature inevitably complex surface reconstructions. Here, we present the B-site interfacial structure in polar (111) and non-polar (001) SrIrO3/SrTiO3 interfaces. The heterostructures were examined using scanning transmission electron microscopy and synchrotron-based coherent Bragg rod analysis. Our results reveal the preference of B-site intermixing across the (111) interface due to the polarity-compensated SrTiO3 substrate surface prior to growth. By comparison, the intermixing at the non-polar (001) interface is negligible. This finding suggests that the intermixing may be necessary to mitigate epitaxy along heavily reconstructed and non-stoichiometric (111) perovskite surfaces. Furthermore, this preferential B-site configuration could allow the geometric design of the interfacial perovskite structure and chemistry to selectively engineer the correlated electronic states of the B-site d-orbital.

Fully Spin-Polarized, Two-Dimensional Hole and Electron Gases at the Highly Polar (111) EuTiO3/SrTiO3 Interface

“…In fact, the excess electrons produced by oxygen vacancies can migrate to the surface to generate electron gas and simultaneously erase the electrostatic divergence. A similar charge transfer mechanism may act in the generation of the 2DEG observed in (111) STO/LAO interfaces − and (111) SrIrO 3 /SrTiO 3 interfaces, with RHEED and STEM images showing ordered structures and flat terraces.…”