Moir\'e Engineering of Nonsymmorphic Symmetries and Hourglass Superconductors

TL;DR

This paper proposes that twisted bilayers of SnS can host a moiré semimetal state with hourglass fermions protected by nonsymmorphic symmetries, which remains robust under interactions and can lead to superconductivity.

Contribution

It introduces a new moiré platform in SnS bilayers with nonsymmorphic symmetry, revealing emergent topological semimetal and superconducting phases through first-principles calculations.

Findings

Moiré heterostructure of SnS hosts hourglass fermions.

Topological Fermi arcs persist under weak interactions.

Superconductivity emerges in the phase diagram.

Abstract

Moir\'e heterostructures hold the promise to provide platforms to tailor strongly correlated and topological states of matter. Here, we theoretically propose the emergence of an effective, rectangular moir\'e lattice in twisted bilayers of SnS with nonsymmorphic symmetry. Based on first-principles calculations, we demonstrate that strong intrinsic spin-orbit interactions render this tunable platform a moir\'e semimetal that hosts 2D hourglass fermions protected by time-reversal symmetry $\mathcal{T}$ and the nonsymmorphic screw rotation symmetry $\widetilde{\mathcal{C}}_{2y}$. We show that topological Fermi arcs connecting pairs of Weyl nodal points in the hourglass dispersion are preserved for weak electron-electron interactions, particularly in regions of superconducting order that emerge in the phase diagram of interaction strength and filling. Our work established moir\'e engineering as an inroad into the realm of correlated topological semimetals and may motivate further topology related researches in moir\'e heterostructures.