Massless Dirac magnons in the two dimensional van der Waals honeycomb magnet CrCl3

Abstract

Two dimensional van der Waals ferromagnets with honeycomb structures are expected to host the bosonic version of Dirac particles in their magnon excitation spectra. Using inelastic neutron scattering, we study spin wave excitations in polycrystalline CrCl${}_3$, which exhibits ferromagnetic honeycomb layers with antiferromagnetic stackings along the $c$-axis. For comparison, polycrystal samples of CrI${}_3$ with different grain sizes are also studied. We find that the powder-averaged spin wave spectrum of CrCl${}_3$ at $T$ = 2 K can be adequately explained by the two dimensional spin Hamiltonian including in-plane Heisenberg exchanges only. The observed excitation does not exhibit noticeable broadening in energy, which is in remarkable contrast to the substantial broadening observed in CrI${}_3$. Based on these results, we conclude that the ferromagnetic phase of CrCl${}_3$ hosts massless Dirac magnons and is thus not topological.

14 pages, 5 figures

References in corpus (7)

• Dirac materials
• Direct photoluminescence probing of ferromagnetism in monolayer two-dimensional CrBr3
• Evolution of interlayer and intralayer magnetism in three atomically thin chromium trihalides
• Magnetic Two-Dimensional Chromium Trihalides: A Theoretical Perspective
• Coexistence of Magnetic Orders in Two-Dimensional Magnet CrI${}_3$
• Magnetic field effect on topological spin excitations in CrI${}_3$
• Topological magnon insulator spin excitations in the two-dimensional ferromagnet CrBr${}_3$

Cited by in corpus (13)

• Spiral spin-liquid on a honeycomb lattice
• Thermal Evolution of Dirac Magnons in the Honeycomb Ferromagnet CrBr${}_3$
• Gapless Dirac magnons in CrCl${}_3$
• Gaps in Topological Magnon Spectra: Intrinsic vs. Extrinsic Effects
• Stacking-dependent topological magnons in bilayer CrI${}_3$
• Tunable magnon topology in monolayer CrI${}_3$ under external stimuli
• Linear response theories for interatomic exchange interactions
• First-principles study of the gap in the spin excitation spectrum of the CrI${}_3$ honeycomb ferromagnet
• Antiferromagnetic-ferromagnetic homostructures with Dirac magnons in van der Waals magnet CrI${}_3$
• Magnon dispersion and spin transport in CrCl${}_3$ bilayers under different strain-induced magnetic states
• Transport of Dirac magnons driven by gauge fields
• Cavity based sensing of antiferromagnetic canting and nonzero-momentum spin waves in a van der Waals cavity-magnon-polariton system
• Probing GHz Spin Dynamics Across Magnetic Phase Transitions in CrCl3 Nanoflakes Using Nitrogen-Vacancy Microscopy