Analytic description of spin waves in dipolar/octupolar pyrochlore magnets

TL;DR

This paper analytically derives spin wave modes in dipolar-octupolar pyrochlore magnets like Nd2Zr2O7, including effects of a breathing mode perturbation on the magnon spectrum.

Contribution

It provides explicit analytic forms for spin waves in these complex magnets and explores the impact of breathing mode perturbations on their dispersion relations.

Findings

Analytic spin wave solutions for dipolar-octupolar pyrochlores.

Breathing mode lifts degeneracy in the spin wave spectrum.

Full magnonic Hamiltonian diagonalization within linear spin wave approximation.

Abstract

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.