Flat-band spin density wave in twisted bilayer materials

TL;DR

This paper investigates the origin of magnetism in twisted bilayer materials, revealing that it arises from spin splitting caused by an increased exchange interaction relative to band dispersion, using advanced electronic structure calculations.

Contribution

It introduces a novel explanation for magnetism in twisted bilayer systems based on spin splitting and exchange interactions, supported by large-scale calculations.

Findings

Magnetism originates from spin splitting in twisted bilayers.

Enhanced exchange interaction relative to band dispersion drives magnetism.

The study provides a new theoretical framework for understanding magnetism in these materials.

Abstract

Twisting is a novel technique for creating strongly correlated effects in two-dimensional bilayered materials, and can tunably generate nontrivial topological properties, magnetism, and superconductivity. Magnetism is particularly significant as it can both compete with superconductivity and lead to the emergence of nontrivial topological states. However, the origin of magnetism in twisted structures remains a subject of controversy. Using self-developed large-scale electronic structure calculations, we propose the magnetism in these twisted bilayer systems originates from spin splitting induced by the enhanced ratio of the exchange interaction to band dispersion.