Emergent topological phenomena in thin films of pyrochlore iridates

With the recent development of thin film and artificial superstructure growth technique, it is possible to fabricate a system, moothly connecting the two-dimensions (2D) and three-dimensions (3D). In this work we unveil the dimensional crossover of emergent topological phenomena. In particular, by focusing on the thin film of pyrochlore iridate antiferromagnets grown along the [111] direction, we demonstrate that it can show giant anomalous Hall conductance, which is as large as the Hall conductance of 3D quantum Hall insulators, even though there is no Hall effect in 3D bulk material. In addition, we show the emergence of a genuine new topological phase, dubbed the anti-Chern insulator, which is realized only in thin films. This shows that the thin film of topological materials is a new platform to search unexplored novel topological phenomena.