Chiral magnetism and helimagnons in a pyrochlore antiferromagnet

Abstract

Recent neutron scattering measurements on the spinel CdCr2O4 revealed a rare example of helical magnetic order in geometrically frustrated pyrochlore antiferromagnet. The spin spiral characterized by an incommensurate wavevector Q = 2pi (0, delta, 1) with delta ~0.09 is accompanied by a tetragonal distortion. Here we conduct a systematic study on the magnetic ground state resulting from the interplay between the Dzyaloshinskii-Moriya interaction and further neighbor exchange couplings, two of the most important mechanisms for stabilizing incommensurate spin orders. We compute the low-energy spin-wave spectrum based on a microscopic spin Hamiltonian and find a dispersion relation characteristic of the helimagnons. By numerically integrating the Landau-Lifshitz-Gilbert equation with realistic model parameters, an overall agreement between experiment and the numerical spectrum, lending further support to the view that a softened optical phonon triggers the magnetic transition and endows the lattice a chirality.

13 pages, 10 figures

References in corpus (8)

• Electronic band structure and exchange coupling constants in ACr2X4 spinels
• Spin-phonon coupling in antiferromagnetic chromium spinels
• Theory of electromagnon in the multiferroic Mn perovskites: Vital role of higher harmonic components of the spiral spin order
• Mechanisms of degeneracy breaking in pyrochlore antiferromagnets
• 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

Cited by in corpus (1)

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