Moiré magnetism and moiré excitons in twisted CrSBr bilayers

• 成果类型: Article
• 署名作者: Liu, Junyi; Zhang, Xu; Lu, Gang
• 署名单位: California State University System; California State University Northridge
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-9941
• DOI: 10.1073/pnas.2413326121
• 发表日期: 2025-01-07
• 关键词: electron-hole excitations; total-energy calculations; charge separation; optical-properties; semiconductors; condensation; coherence; emitters; SPECTRA; STATES

摘要

Moir & eacute; excitons and moir & eacute; magnetism are essential to semiconducting van der Waals magnets. In this work, we perform a comprehensive first- principles study to elucidate the interplay of electronic excitation and magnetism in twisted magnetic CrSBr bilayers. We predict a twist- induced quantum phase transition for interlayer magnetic coupling and estimate the critical twist angle below which moir & eacute; magnetism with mixed ferromagnetic and antiferromagnetic domains could emerge. Localized one- dimensional moir & eacute; excitons are stable if the interlayer coupling is ferromagnetic and become unstable if the coupling turns to antiferromagnetic. Exciton energy modulation by magnons is estimated and dependence of exciton oscillator strength on the twist angle and interlayer coupling is analyzed. An orthogonally twisted bilayer is revealed to exhibit layer- dependent, anisotropic optical transitions. Electric field is shown to induce net magnetic moments in moir & eacute; excitons, endowing them with exceedingly long lifetimes. Our work lays the foundation for using magnetic moir & eacute; bilayers in spintronic, optoelectronic, and quantum information applications.