We derive analytic forms for spin waves in pyrochlore magnets with dipolar-octupolar interactions, such as ${ \rm Nd}_2{ \rm Zr}_2{ \rm O}_7$. We obtain full knowledge of the diagonalized magnonic Hamiltonian within the linear spin wave approximation. We also consider the effect of a "breathing mode" as a perturbation of this system. The breathing mode lifts the degeneracy of the upper band of the spin wave dispersion along the direction $X\to W$ in $k$-space.
Categories: cond-mat.str-el