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

References in corpus (7)

• Restoring the density-gradient expansion for exchange in solids and surfaces
• Generalized gradient approximation for solids and their surfaces
• Spin-driven ferroelectricity and possible antiferroelectricity in triangular lattice antiferromagnets ACrO2 (A = Cu, Ag, Li, or Na)
• Electromagnons in multiferroic RMn2O5 compounds and their microscopic origin
• Molecular spin resonance in the geometrically frustrated MgCr2O4 magnet by inelastic neutron scattering
• Using ultrashort optical pulses to couple ferroelectric and ferromagnetic order in an oxide heterostructure
• Spin-lattice order in frustrated ZnCr2O4

Cited by in corpus (4)

• Evidence for magnon-phonon coupling in the topological magnet Cu${}_3$TeO${}_6$
• Magnon-polaron excitations in the noncollinear antiferromagnet Mn${}_3$Ge
• Magnon-phonon coupling effects on the indirect K-edge resonant inelastic X-ray scattering spectrum of a 2D Heisenberg antiferromagnet
• Momentum-dependent magnon lifetime in the metallic non-collinear triangular antiferromagnet CrB2