Raman scattering from Higgs mode oscillations in the two-dimensional antiferromagnet Ca${}_2$RuO${}_4$

Abstract

We present and analyze Raman spectra of the Mott insulator Ca${}_2$RuO${}_4$, whose quasi-two-dimensional antiferromagnetic order has been described as a condensate of low-lying spin-orbit excitons with angular momentum $J_{eff}=1$. In the $A_g$ polarization geometry, the amplitude (Higgs) mode of the spin-orbit condensate is directly probed in the scalar channel, thus avoiding infrared-singular magnon contributions. In the $B_{1g}$ geometry, we observe a single-magnon peak as well as two-magnon and two-Higgs excitations. Model calculations using exact diagonalization quantitatively agree with the observations. Together with recent neutron scattering data, our study provides strong evidence for excitonic magnetism in Ca${}_2$RuO${}_4$ and points out new perspectives for research on the Higgs mode in two dimensions.

arXiv comment5 pages, 4 figures; small changes through the text, references updated

References in corpus (21)

• Bose-Einstein Condensation in Magnetic Insulators
• Amplitude / Higgs Modes in Condensed Matter Physics
• Quantum Criticality
• The `Higgs' Amplitude Mode at the Two-Dimensional Superfluid-Mott Insulator Transition
• Quantum Magnets under Pressure: Controlling Elementary Excitations in TlCuCl3
• Excitonic Magnetism in Van Vleck-type d^4 Mott Insulators
• Visibility of the Amplitude (Higgs) Mode in Condensed Matter
• Higgs mode and its decay in a two dimensional antiferromagnet
• Spectral functions of the Higgs mode near two-dimensional quantum critical points
• The Higgs mode in a two-dimensional superfluid
• Fate of the Higgs mode near quantum criticality
• Pressure-Tuned Collapse of the Mott-Like State in Ca_{n+1}Ru_nO_{3n+1} (n=1,2): Raman Spectroscopic Studies
• Dynamics and Conductivity Near Quantum Criticality
• Higgs amplitude mode in the vicinity of a $(2+1)$-dimensional quantum critical point
• Higgs amplitude mode in the vicinity of a $(2+1)$-dimensional quantum critical point: a nonperturbative renormalization-group approach
• Highly anisotropic magnon dispersion in Ca2RuO4: evidence for strong spin orbit coupling
• Universal Properties of the Higgs Resonance in (2+1)-Dimensional U(1) Critical Systems
• Higgs Mode and Magnon Interactions in 2D Quantum Antiferromagnets from Raman Scattering
• Spectral function of the Higgs mode in 4-\varepsilon dimensions
• Lattice dynamics and the electron-phonon interaction in Ca${}_2$RuO${}_4$
• Raman scattering studies of spin, charge, and lattice dynamics in Ca_{2-x}Sr_{x}RuO_{4} (0 =< x < 0.2)

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