Insights on magnon topology and valley-polarization in 2D bilayer quantum magnets

Abstract

The rich and unconventional physics in layered 2D magnets can open new avenues for topological magnonics and magnon valleytronics. In particular, two-dimensional (2D) bilayer quantum magnets are gaining increasing attention due to their intriguing stacking-dependent magnetism, controllable ground states, and topological excitations induced by magnetic spin-orbit couplings (SOCs). Despite the substantial research on these materials, their topological features remain widely unexplored to date. The present study comprehensively investigates the magnon topology and magnon valley-polarization in honeycomb bilayers with collinear magnetic order. We elucidate the separate and combined effects of the SOC, magnetic ground-states, stacking order, and inversion symmetry breaking on the topological phases, magnon valley transport, and the Hall and Nernst effects. The comprehensive analysis suggests clues to determine the SOC's nature and predicts unconventional Hall and Nernst conductivities in topologically trivial phases. We further report on novel bandgap closures in layered antiferromagnets and detail their topological implications. We believe the present study provides important insights into the fundamental physics and technological potentials of topological 2D magnons.

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Cited by in corpus (7)

• Topological Phases in Magnonics
• Whirling interlayer fields as a source of stable topological order in moiré CrI3
• Non-linear magnon transport in a bilayer van der Waals antiferromagnets
• Superexchange and spin-orbit coupling in monolayer and bilayer chromium trihalides
• Magnon Hall effect in antiferromagnetic lattices
• Momentum-space theory for topological magnons in 2D ferromagnetic skyrmion lattices
• Chirality-selective topological magnon phase transition induced by interplay of anisotropic exchange interactions in honeycomb ferromagnet