Universal exchange-driven phonon splitting in antiferromagnets

Abstract

We report a linear dependence of the phonon splitting Δωon the non-dominant exchange coupling constant J_{nd} in the antiferromagnetic transition-metal monoxides MnO, FeO, CoO, NiO, and in the frustrated antiferromagnetic oxide spinels CdCr2O4, MgCr2O4, and ZnCr2O4. It directly confirms the theoretical prediction of an exchange induced splitting of the zone-centre optical phonon for the monoxides and explains the magnitude and the change of sign of the phonon splitting on changing the sign of the non-dominant exchange also in the frustrated oxide spinels. The experimentally found linear relation \hbarΔω= βJ_{nd} S^2 with slope β= 3.7 describes the splitting for both systems and agrees with the observations in the antiferromagnets KCoF3 and KNiF3 with perovskite structure and negligible next-nearest neighbour coupling. The common behavior found for very different classes of cubic antiferromagnets suggests a universal dependence of the exchange-induced phonon splitting at the antiferromagnetic transition on the non-dominant exchange coupling.

5 pages, 4 figures

References in corpus (12)

• Dynamical magneto-electric coupling in helical magnets
• Magnetic Moment Collapse-Driven Mott Transition in MnO
• Magnetic-induced phonon anisotropy in ZnCr${}_2$O${}_4$ from first principles
• Molecular spin resonance in the geometrically frustrated MgCr2O4 magnet by inelastic neutron scattering
• Partial order from disorder in a classical pyrochlore antiferromagnet
• Wüstite: Electric, thermodynamic and optical properties of FeO
• Optical Spectroscopy in CoO: Phonons, Electric, and Magnetic Excitations
• Spin-phonon coupling in ZnCr2Se4
• Spin phonon coupling in frustrated magnet CdCr${}_2$O${}_4$
• Magnetic-order induced phonon splitting in MnO from far-infrared spectroscopy
• Heisenberg exchange in magnetic monoxides
• Optical properties of ZnCr2Se4 - Spin-phonon coupling and electronic d-d-like excitations

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• Optical conductivity in multiferroic GaV${}_4$S${}_8$ and GeV${}_4$S${}_8$: Phonons and electronic transitions
• Magnetically induced phonon splitting in ACr${}_2$O${}_4$ spinels from first principles
• Exciton-magnon transitions in the frustrated chromium antiferromagnets CuCrO2, alpha-CaCr2O4, CdCr2O4, and ZnCr2O4
• Successive dielectric anomalies and magnetoelectric coupling in honeycomb Fe${}_4$Nb${}_2$O${}_9$
• Electromagnon in ferrimagnetic eps-Fe2O3 nanograin ceramics
• Evolution of optical properties of chromium spinels CdCr${}_2$O${}_4$, HgCr${}_2$S${}_4$, and ZnCr${}_2$Se${}_4$ under high pressure
• Pulsed Laser Deposition of Rocksalt Magnetic Binary Oxides
• Influence of isolated and clustered defects on electronic and dielectric properties of wustite
• Electronic structure and polaronic charge distributions of Fe vacancy clusters in Fe${}_{1-x}$O
• Polar phonons and magnetic excitations in the antiferromagnet CoF${}_2$
• Surface phonons of NiO(001) ultrathin films grown pseudomorphically on Ag(001)
• Lattice dynamics and spin-phonon interaction in strained NiO films
• On the complexity of spinels: Magnetic, electronic, and polar ground states
• Spin-phonon interaction increased by compressive strain in antiferromagnetic MnO thin films