# Transition-Metal Oxide (111) bilayers

## TL;DR

This paper reviews theoretical predictions that transition-metal oxide (111) bilayers can host exotic electronic phenomena like quantum Hall effects and topological insulators, offering an alternative to van der Waals materials.

## Contribution

It demonstrates that TMOs grown along the [111] axis can be engineered to exhibit quantum Hall effects and topological states, highlighting the role of strong correlations.

## Key findings

- Prediction of quantum Hall effects in TMO heterostructures
- Support for two-dimensional topological insulating states
- Enrichment of phenomena due to strong electron correlations

## Abstract

Correlated electron systems on a honeycomb lattice have emerged as a fertile playground to explore exotic electronic phenomena. Theoretical and experimental work has appeared to realize novel behavior, including quantum Hall effects and valleytronics, mainly focusing on van der Waals compounds, such as graphene, chalcogenides, and halides. In this article, we review our theoretical study on perovskite transition-metal oxides (TMOs) as an alternative system to realize such exotic phenomena. We demonstrate that novel quantum Hall effects and related phenomena associated with the honeycomb structure could be artificially designed by such TMOs by growing their heterostructures along the [111] crystallographic axis. One of the important predictions is that such TMO heterostructures could support two-dimensional topological insulating states. The strong correlation effects inherent to TM $d$ electrons further enrich the behavior.