Strong electronic correlation and strain effects at the interfaces between polar and nonpolar complex oxides

TL;DR

This study explores how different polar/nonpolar oxide interfaces, beyond LaAlO$_3$/SrTiO$_3$, can produce two-dimensional electron gases, with properties influenced by strain and strong electronic correlations, offering new ways to tune interface functionalities.

Contribution

It demonstrates that various ABO$_3$/SrTiO$_3$ interfaces can generate 2DEG, highlighting the roles of strain and correlation effects, expanding understanding beyond LaAlO$_3$/SrTiO$_3$ systems.

Findings

All studied interfaces produce 2DEG, confirming electronic reconstruction as the mechanism.

Electrical properties are strongly affected by interface strain.

Strong correlation effects influence the interface behavior.

Abstract

The interface between the polar LaAlO$_3$ and nonpolar SrTiO$_3$ layers has been shown to exhibit various electronic and magnetic phases such as two dimensional electron gas, superconductivity, magnetism and electronic phase separation. These rich phases are expected due to the strong interplay between charge, spin and orbital degree of freedom at the interface between these complex oxides, leading to the electronic reconstruction in this system. However, until now all of these new properties have been studied extensively based on the interfaces which involve a polar LaAlO$_3$ layer. To investigate the role of the A and B cationic sites of the ABO$_3$ polar layer, here we study various combinations of polar/nonpolar oxide (NdAlO$_3$/SrTiO$_3$, PrAlO$_3$/SrTiO$_3$ and NdGaO$_3$/SrTiO$_3$) interfaces which are similar in nature to LaAlO$_3$/SrTiO$_3$ interface. Our results show that all of these new interfaces can also produce 2DEG at their interfaces, supporting the idea that the electronic reconstruction is the driving mechanism for the creation of the 2DEG at these oxide interfaces. Furthermore, the electrical properties of these interfaces are shown to be strongly governed by the interface strain and strong correlation effects provided by the polar layers. Our observations may provide a novel approach to further tune the properties of the 2DEG at the selected polar/nonpolar oxide interfaces.