Magnon Hall Effect without Dzyaloshinskii-Moriya Interaction

TL;DR

This paper demonstrates that topological magnon effects can occur without Dzyaloshinskii-Moriya interaction, induced instead by a magnetic field creating non-coplanar spin textures in frustrated star-lattice antiferromagnets.

Contribution

It reveals a new mechanism for topological magnon effects driven by magnetic field-induced non-coplanar spins, independent of DMI or magnetic order.

Findings

Magnetic field induces non-coplanar spin textures with scalar chirality.

Topological magnon effects can occur without DMI in frustrated lattices.

Potential realization in Polymeric Iron (III) Acetate.

Abstract

Topological magnon bands and magnon Hall effect in insulating collinear ferromagnets are induced by the Dzyaloshinskii-Moriya interaction (DMI) even at zero magnetic field. In the geometrically frustrated star lattice, a coplanar/noncollinear $\mathbf q=0$ magnetic ordering may be present due to spin frustration. This magnetic structure, however, does not exhibit topological magnon effects even with DMI in contrast to collinear ferromagnets. We show that a magnetic field applied perpendicular to the star plane induces a non-coplanar spin configuration with nonzero spin scalar chirality, which provides topological effects without the need of DMI. The non-coplanar spin texture originates from the topology of the spin configurations and does not need the presence of DMI or magnetic ordering, which suggests that this phenomenon may be present in the chiral spin liquid phases of frustrated magnetic systems. We propose that these anomalous topological magnon effects can be accessible in Polymeric Iron (III) Acetate --- a star-lattice antiferromagnet with both spin frustration and long-range magnetic ordering.