Weyl magnons in breathing pyrochlore antiferromagnets

Weyl magnons in breathing pyrochlore antiferromagnets

Frustrated quantum magnets not only provide exotic ground states and unusual magnetic structures, but also support unconventional excitations in many cases. Using a physically relevant spin model for a breathing pyrochlore lattice, we discuss the presence of topological linear band crossings of magnons in antiferromagnets. These are the analogues of Weyl fermions in electronic systems, which we...

Depleted pyrochlore antiferromagnets

I consider the class of “depleted pyrochlore” lattices of corner-sharing triangles, made by removing spins from a pyrochlore lattice such that every tetrahedron loses exactly one. Previously known examples are the “hyperkagome” and “kagome staircase”. I give criteria in terms of loops for whether a given depleted lattice can order analogous to the kagome “ √ 3× √ 3” state, and also show how the...

Critical properties of highly frustrated pyrochlore antiferromagnets.

We argue that the analysis of Reimers et al. (1992)] of their Monte Carlo data on the Heisenberg pyrochlore antiferromag-net, which suggests a new universality class, is not conclusive. By re-analysis of their data, we demonstrate asymptotic volume dependence in some ther-modynamic quantities, which suggests the possibility that the transition may be first order.

Weyl and nodal ring magnons in three-dimensional honeycomb lattices

We study the topological properties of magnon excitations in a wide class of three dimensional (3D) honeycomb lattices with ferromagnetic ground states. It is found that they host nodal ring magnon excitations. These rings locate on the same plane in the momentum space. The rings can be gapped by Dzyaloshinskii-Moriya (DM) interactions to form two Weyl points with opposite charges. We explicitl...

Explorer Breathing Pyrochlore Lattice Realized in A - Site Ordered Spinel Oxides