Dirac magnons in honeycomb ferromagnets

Abstract

The discovery of the Dirac electron dispersion in graphene led to the question of the Dirac cone stability with respect to interactions. Coulomb interactions between electrons were shown to induce a logarithmic renormalization of the Dirac dispersion. With a rapid expansion of the list of compounds and quasiparticle bands with linear band touching, the concept of bosonic Dirac materials has emerged. We consider a specific case of ferromagnets consisting of the Van der Waals-bonded stacks of honeycomb layers, e.g chromium trihalides CrX3 (X = F, Cl, Br and I), that display two spin wave modes with energy dispersion similar to that for the electrons in graphene. At the single particle level, these materials resemble their fermionic counterparts. However, how different particle statistics and interactions affect the stability of Dirac cones has yet to be determined. To address the role of interacting Dirac magnons, we expand the theory of ferromagnets beyond the standard Dyson theory to a case of non-Bravais honeycomb layers. We demonstrate that magnon-magnon interactions lead to a significant momentum-dependent renormalization of the bare band structure in addition to strongly momentum-dependent magnon lifetimes. We show that our theory qualitatively accounts for hitherto unexplained anomalies in a nearly half century old magnetic neutron scattering data for CrBr3. We also show that honeycomb ferromagnets display dispersive surface and edge states, unlike their electronic analogs.

References in corpus (10)

• The electronic properties of graphene
• Reflection-Free One-Way Edge Modes in a Gyromagnetic Photonic Crystal
• Analogs of quantum Hall effect edge states in photonic crystals
• Dirac materials
• Topological Magnon Insulator in Insulating Ferromagnet
• Spontaneous Magnon Decays
• Dimensional crossover in topological matter: Evolution of the multiple Dirac point in the layered system to the flat band on the surface
• Dirac-like plasmons in honeycomb lattices of metallic nanoparticles
• Magnonic quantum Hall effect and Wiedemann-Franz law
• Magnon nodal-line semimetals and drumhead surface states in anisotropic pyrochlore ferromagnets

Cited by in corpus (18)

• Direct photoluminescence probing of ferromagnetism in monolayer two-dimensional CrBr3
• Magnon Blockade in a Hybrid Ferromagnet-Superconductor Quantum System
• Magnetic field effect on topological spin excitations in CrI${}_3$
• Topological magnon insulator spin excitations in the two-dimensional ferromagnet CrBr${}_3$
• Moiré magnons in twisted bilayer magnets with collinear order
• Spin caloritronics in a CrBr${}_3$-based magnetic van der Waals heterostructure
• Giant thermal magnetoconductivity in CrCl${}_3$ and a general model for spin-phonon scattering
• Evidence for biquadratic exchange in the quasi-two-dimensional antiferromagnet FePS${}_3$
• Dipolar spin waves in uniaxial easy-axis antiferromagnets: A natural topological nodal-line semimetal
• Stacking-dependent topological magnons in bilayer CrI${}_3$
• Two-dimensional ferromagnetic spin-orbital excitations in the honeycomb VI${}_3$
• 2D ferromagnetism at finite temperatures under quantum scrutiny
• Magnon quantum anomalies in Weyl ferromagnets
• Symmetry Analysis of Tensors in the Honeycomb Lattice of Edge-Sharing Octahedra
• Spin Waves and Dirac Magnons in a Honeycomb Lattice Zig-zag Antiferromagnet BaNi2(AsO4)2
• Discretized dynamics of exchange spin wave bulk and edge modes in honeycomb nanoribbons with armchair edge boundaries
• Quantum matter and gravitation: photons in a waveguide
• Topological excitations in quasi two-dimensional quantum magnets with weak interlayer interactions