Electromagnon dispersion probed by inelastic x-ray scattering

Abstract

Inelastic x-ray scattering with meV energy resolution (IXS) is an ideal tool to measure collective excitations in solids and liquids. In non-resonant scattering condition, the cross section is strongly dominated by lattice vibrations (phonons). However, it is possible to probe additional degrees of freedom such as magnetic fluctuations that are strongly coupled to the phonons. The IXS spectrum of the coupled system will contain not only the phonon dispersion (majority component) but also the so far undetected magnetic correlation function (minority component). Here we report the discovery of strong magnon-phonon coupling in LiCrO${}_2$ that enables the measurement of magnetic correlations throughout the Brillouin-zone via IXS. We found electromagnon excitations and electric dipole active two-magnon excitations in the magnetically ordered phase and paraelectromagnons in the paramagnetic phase of LiCrO${}_2$. We predict that the numerous group of (frustrated) magnets with dominant direct exchange and non-collinear magnetism shows similarly strong coupling and surprisingly large and measurable IXS cross section for magnons and multi-magnon processes.

7 pages, 3 figures

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• Crossover from itinerant to localized magnetic excitations through the metal-insulator transition in NaOsO${}_{\text{3}}$
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• Interplay between spin dynamics and crystal field in multiferroic compound HoMnO${}_3$
• Strong-coupling magnetophononics: Self-blocking, phonon-bitriplons, and spin-band engineering
• The Duel of Magnetic Interactions & Structural Instabilities: Itinerant Frustration in the Triangular Lattice Compound LiCrSe${}_2$
• Magnon-phonon coupling effects on the indirect K-edge resonant inelastic X-ray scattering spectrum of a 2D Heisenberg antiferromagnet
• Nuclear and magnetic spin structure of the antiferromagnetic triangular lattice compound LiCrTe${}_2$ investigated by ${\mu }^{+}$SR as well as neutron and X-ray diffraction
• Synthesis and Anisotropic Magnetic Properties of LiCrTe${}_2$ Single Crystals with a Triangular-Lattice Antiferromagnetic Structure
• Momentum-dependent magnon lifetime in the metallic non-collinear triangular antiferromagnet CrB2
• Exchange striction induced thermal Hall effect in van der Waals antiferromagnet MnPS${}_3$
• Hierarchical excitations from correlated spin tetrahedra on the breathing pyrochlore lattice
• Structural Modulation and Enhanced Magnetic Ordering in Incommensurate K${}_{1-x}$CrSe${}_2$ Crystals
• Lattice dynamics in the double-helix antiferromagnet FeP
• Magnons from time-dependent density-functional perturbation theory and nonempirical Hubbard functionals
• Probing emergent QED in quantum spin ice via Raman scattering of phonons: shallow inelastic scattering and pair production
• Evidence of magnetoelectronic electromagnon mediated transport in flexoelectronic heterostructures
• Universal fluctuating regime in triangular chromate antiferromagnets