We report on the impact of the Dzyaloshinskii-Moriya interaction on the coherent backscattering of spin waves in a disordered magnetic material. This interaction breaks the inversion symmetry of the spin-wave dispersion relation, such that $\omega_\mathbf{ k} = \omega_{ 2\mathbf{ K}^\mathrm{ I}-\mathbf{ k}} \neq \omega_{ -\mathbf{ k}}$, where $\mathbf{ K}^\mathrm{ I}$ is related to the Dzyaloshinskii-Moriya vectors. As a result of numerical investigations we find that the backscattering peak of a wave packet with initial wave vector $\mathbf{ k}_0$ shifts from $-\mathbf{ k}_0$ to $2\mathbf{ K}^\mathrm{ I}-\mathbf{ k}_0$, such that the backscattering wave vector and the initial wave vector are in general no longer antiparallel. The shifted coherence condition is explained by a diagrammatic approach and opens up an avenue to measure sign and magnitude of the Dzyaloshinskii-Moriya interaction in weakly disordered chiral magnets.
Categories: cond-mat.mes-hall