Nodal-line semimetal superlattices

TL;DR

This paper explores the effects of multilayer stacking on nodal-line semimetals, revealing shape changes in nodal lines and potential emergence of quantum anomalous Hall phases depending on magnetization direction.

Contribution

It provides a theoretical analysis of multilayer configurations of nodal-line semimetals, including the impact of stacking orientation and magnetization on their topological phases.

Findings

Nodal lines change shape due to Brillouin zone folding in parallel stacking.

Magnetization can induce quantum anomalous Hall phases.

Weyl semimetal phase appears when magnetization aligns with certain symmetry axes.

Abstract

Spatial modulations, such as multilayers, to realize topological materials have recently been studied in theoretical and experimental works. In this paper, we investigate properties of the multilayers of the nodal-line semimetal (NLS) and the normal insulator. We consider two types of multilayers, with the stacking direction being perpendicular or parallel to the plane where the nodal line lies. In particular, we show that when the stacking direction is parallel to the plane, the nodal lines remain but they change their shapes because of the folding of the Brillouin zone. We also study the multilayers with magnetization. One can expect that the quantum anomalous Hall (QAH) phase emerges in some cases, depending on the direction of the magnetization. If the magnetization is along the $C_2$-invariant axis, the multilayer becomes the Weyl semimetal phase if the $C_2$-invariant axis intersects the nodal lines, and otherwise it becomes the QAH phases.