Non-reciprocal magnons in non-centrosymmetric MnSi

Using two cold-neutron triple-axis spectrometers we have succeeded in fully mapping out the field-dependent evolution of the non-reciprocal magnon dispersion relations in all magnetic phases of MnSi. The non-reciprocal nature of the dispersion manifests itself in a full asymmetry (non-reciprocity) of the dynamical structure factor $S(q,E,{\mu }_0{H}_{int})$ with respect to flipping either the direction of the applied magnetic field ${\mu }_0{H}_{int}$, the reduced momentum transfer $q$, or the energy transfer $E$.