Orbital Angular Momentum of Magnons in Collinear Magnets

We study the orbital angular momentum of magnons for collinear ferromagnet (FM) and antiferro-magnetic (AF) systems with nontrivial networks of exchange interactions. The orbital angular momentum of magnons for AF and FM zigzag and honeycomb lattices becomes nonzero when the lattice contains two inequivalent sites and is largest at the avoided-crossing points or extremum of the frequency bands. Hence, the arrangement of exchange interactions may play a more important role at producing the orbital angular momentum of magnons than the spin-orbit coupling energy and the resulting noncollinear arrangement of spins.

Automated summary

This study investigates the orbital angular momentum of magnons in collinear ferromagnetic and antiferromagnetic systems with nontrivial networks of exchange interactions. The results show that the orbital angular momentum of magnons becomes nonzero in zigzag and honeycomb lattices when the lattice contains two inequivalent sites and reaches its peak at avoided-crossing points or extremum of the frequency bands. Thus, the arrangement of exchange interactions may play a more significant role in generating the orbital angular momentum of magnons compared to spin-orbit coupling energy and the resulting noncollinear arrangement of spins.