Dzyaloshinskii-Moriya interaction and spin re-orientation transition in the frustrated kagome lattice antiferromagnet

TL;DR

This study investigates the magnetic transition in a kagome lattice antiferromagnet, revealing how Dzyaloshinskii-Moriya interactions induce spin reorientation under an external magnetic field, with neutron scattering confirming the spin rotation mechanism.

Contribution

The paper provides the first direct neutron scattering evidence of a 180-degree spin rotation transition driven by Dzyaloshinskii-Moriya interactions in a kagome antiferromagnet.

Findings

Magnetization shows a sudden increase at a critical field H_c.

Neutron scattering confirms the 180-degree spin rotation at the transition.

Dzyaloshinskii-Moriya interaction causes canted moments on kagome planes.

Abstract

Magnetization, specific heat, and neutron scattering measurements were performed to study a magnetic transition in jarosite, a spin-5/2 kagome lattice antiferromagnet. When a magnetic field is applied perpendicular to the kagome plane, magnetizations in the ordered state show a sudden increase at a critical field H_c, indicative of the transition from antiferromagnetic to ferromagnetic states. This sudden increase arises as the spins on alternate kagome planes rotate 180 degrees to ferromagnetically align the canted moments along the field direction. The canted moment on a single kagome plane is a result of the Dzyaloshinskii-Moriya interaction. For H < H_c, the weak ferromagnetic interlayer coupling forces the spins to align in such an arrangement that the canted components on any two adjacent layers are equal and opposite, yielding a zero net magnetic moment. For H > H_c, the Zeeman energy overcomes the interlayer coupling causing the spins on the alternate layers to rotate, aligning the canted moments along the field direction. Neutron scattering measurements provide the first direct evidence of this 180-degree spin rotation at the transition.