Helimagnons in a chiral ground state of the pyrochlore antiferromagnets

Abstract

The Goldstone mode in a helical magnetic phase, also known as the helimagnon, is a propagating mode with a highly anisotropic dispersion relation. Here we study theoretically the helimagnon excitations in a complex chiral ground state of pyrochlore antiferromagnets such as spinel CdCr2O4 and itinerant magnet YMn2. We show that the effective theory of the soft modes in the helical state possesses a symmetry similar to that of smectic liquid crystals. We compute the low-energy spin-wave spectrum based on a microscopic spin Hamiltonian and find a dispersion relation characteristic of the helimagnons. By performing dynamics simulations with realistic model parameters, we also obtain an overall agreement between experiment and the numerical spin-wave spectrum. Our work thus also clarifies the mechanisms that relive the magnetic frustration in these compounds.

5 pages, 3 figures

References in corpus (7)

• Electronic band structure and exchange coupling constants in ACr2X4 spinels
• Theory of electromagnon in the multiferroic Mn perovskites: Vital role of higher harmonic components of the spiral spin order
• Partial order from disorder in a classical pyrochlore antiferromagnet
• Broken parity and a chiral ground state in the frustrated magnet CdCr2O4
• Spin phonon coupling in frustrated magnet CdCr${}_2$O${}_4$
• Ising Like Order by Disorder In The Pyrochlore Antiferromagnet with Dzyaloshinskii-Moriya Interactions
• Spin Structure Factor of the Frustrated Quantum Magnet Cs_2CuCl_4

Cited by in corpus (1)

• Unconventional magnetic field response of the hyperhoneycomb Kitaev magnet $\beta -{\text{Li}}_2{\text{IrO}}_3$