Electron correlation effects on exchange interactions and spin excitations in 2D van der Waals materials

Liqin Ke,Mikhail I Katsnelson

doi:10.1038/s41524-020-00469-2

Liqin Ke, Mikhail I Katsnelson

Open Access

https://doi.org/10.1038/s41524-020-00469-2

Copy DOI

Journal: npj Computational Materials	Publication Date: Jan 4, 2021
Citations: 44	License type: open-access

Affiliation: Ames Laboratory

Abstract

Despite serious effort, the nature of the magnetic interactions and the role of electron-correlation effects in magnetic two-dimensional (2D) van der Waals materials remains elusive. Using CrI3 as a model system, we show that the calculated electronic structure including nonlocal electron correlations yields spin excitations consistent with inelastic neutron-scattering measurements. Remarkably, this approach identifies an unreported correlation-enhanced interlayer super-superexchange, which rotates the magnon Dirac lines off, and introduces a gap along the high-symmetry Γ-K-M path. This discovery provides a different perspective on the gap-opening mechanism observed in CrI3, which was previously associated with spin–orbit coupling through the Dzyaloshinskii–Moriya interaction or Kitaev interaction. Our observation elucidates the critical role of electron correlations on the spin ordering and spin dynamics in magnetic van der Waals materials and demonstrates the necessity of explicit treatment of electron correlations in the broad family of 2D magnetic materials.

Highlights

The intimate interplay between correlated electrons, lattice, and magnetism can result in a rich variety of interesting and important physical phenomena[1]
In this work, using the most studied m2Dv—CrI3—as a prototype, we identify the role of electron correlations on the magnetic interactions and excitations in m2Dv
We demonstrate that the explicit treatment of electron correlations is required to accurately describe the magnetic interactions, especially the interlayer interactions, in m2Dv

Summary

Introduction

The intimate interplay between correlated electrons, lattice, and magnetism can result in a rich variety of interesting and important physical phenomena[1]. We demonstrate that the explicit treatment of electron correlations is required to accurately describe the magnetic interactions, especially the interlayer interactions, in m2Dv. we made the remarkable discovery that a sizable magnon gap opens along the highsymmetry line in CrI3 even without relativistic exchanges.

Results

Conclusion