Tunable magnon Weyl points in ferromagnetic pyrochlores

Abstract

The dispersion relations of magnons in ferromagnetic pyrochlores with Dzyaloshinskii-Moriya interaction is shown to possess Weyl points, i.\,e., pairs of topological nontrivial crossings of two magnon branches with opposite topological charge. As a consequence of their topological nature, their projections onto a surface are connected by magnon arcs, thereby resembling closely Fermi arcs of electronic Weyl semimetals. On top of this, the positions of the Weyl points in reciprocal space can be tuned widely by an external magnetic field: rotated within the surface plane, the Weyl points and magnon arcs are rotated as well; tilting the magnetic field out-of-plane shifts the Weyl points toward the center $\bar{\Gamma }$ of the surface Brillouin zone. The theory is valid for the class of ferromagnetic pyrochlores, i.\,e., three-dimensional extensions of topological magnon insulators on kagome lattices. In this Letter, we focus on the $(111)$ surface, identify candidates of established ferromagnetic pyrochlores which apply to the considered spin model, and suggest experiments for the detection of the topological features.

5 pages, 5 figures

References in corpus (5)

• Observation of the Magnon Hall Effect
• Theoretical prediction of rotating magnon wavepacket in ferromagnets
• Topological Magnon Insulator in Insulating Ferromagnet
• Weyl spin liquids
• Spin wave spectrum of the quantum ferromagnet on the pyrochlore lattice Lu2V2O7

Cited by in corpus (8)

• Topological Magnetic Phase in the Candidate Weyl Semimetal CeAlGe
• Topological Thermal Hall Effect in Frustrated Kagomé Antiferromagnets
• Chiral anomaly of Weyl magnons in stacked honeycomb ferromagnets
• Spin Currents and Magnon Dynamics in Insulating Magnets
• Magnon nodal-line semimetals and drumhead surface states in anisotropic pyrochlore ferromagnets
• Universal phase transition and band structures for spinless nodal-line and Weyl semimetals
• Magnon quantum anomalies in Weyl ferromagnets
• Instability and topological robustness of Weyl semimetals against Coulomb interaction